Appearing for the first time in Japan in 2000, with the references SKX779 (black dial) and SKX781 (orange dial), these diving watches with a “grotesque” appearance immediately divided enthusiasts.
Renamed Seiko Monster because of their design, they are loved by some and hated by others, and over the years they have been able to attract the attention of many collectors.
In this guide we will see all the models released from the beginning to today (updated March 2022).
First generation
The two iconic black and orange Monsters of the first generation housed the 7S26 automatic caliber, the same present in the famous SKX007 and SKX009. This movement, used in many Seiko entry-levels starting from the second half of the 90s, was affordable but robust, and characterized by the absence of manual winding and hacking.
Certified for diving up to 200 meters, the Black and Orange Monster were sold at affordable prices, around 250 USD.
A characteristic feature of the first generation, which will subsequently be lost, are the seconds written alongside the indices on the dial.
Classic Black Monster
Ref: SKX779 (7S26-0350)
Caliber: 7S26
Year: 2000
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Classic Orange Monster
Ref: SKX781 (7S26-0350)
Caliber: 7S26
Year: 2000
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Black Monster (North America)
Ref: SKXA43 (7S26-0351)
Caliber: 7S26
42mm stainless steel case, Hardlex crystal, screw-down crown, 21 jewels, 41 hour power reserve, 21,600 bph.
Orange Monster (North America)
Ref: SKXA45 – SKXA37 (7S26-0351)
Caliber: 7S26
Year: 2002
42mm stainless steel case, Hardlex crystal, screw-down crown, 21 jewels, 41 hour power reserve, 21,600 bph.
Limited Editions of the first generation
After the first models, Seiko presented Limited Editions in various colors, dedicated almost exclusively to the Asian market, and in particular to Thailand, a country where the Monsters apparently enjoyed great success.
As a movement we find the 7S36, which is very similar to the previous 7S26 but with the addition of two jewels.
These brightly colored editions, produced in limited numbers, have become a cult object for some collectors, and are occasionally sold at auction at much higher prices than they were on retail (even more than 10 times higher).
Yellow Monster
Ref: SKZ203 (7S36-01B0)
Caliber: 7S36
Limited edition of 300 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 23 jewels, 41 hours of power reserve, 21,600 bph.
Blue Monster
Ref: SKZ213 (7S36-01G0)
Caliber: 7S36
Limited edition of 1800 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 23 jewels, 41 hours of power reserve, 21,600 bph.
Red Monster
Ref: SKZ243 (7S36-01B0)
Caliber: 7S36
Limited edition of 1313 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 23 jewels, 41 hours of power reserve, 21,600 bph.
Green Monster
Ref: SKZ277 (7S36-03W0)
Caliber: 7S36
Limited edition of 1881 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 23 jewels, 41 hours of power reserve, 21,600 bph.
Snow Monster
Ref: SKZ331 (7S36-05D0)
Caliber: 7S36
Limited edition of 2555 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 23 jewels, 41 hours of power reserve, 21,600 bph.
Night Monsters
In 2007, Seiko introduced another series of first generation Monsters to Japan, featuring a black case and bracelet.
Orange Night Monster
Ref: SZEN001 (7S26-03G0)
Caliber: 7S26
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Black Night Monster
Ref: SZEN002 (7S26-03G0)
Caliber: 7S26
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
White Night Monster
Ref: SZEN006 (7S26-03G0)
Caliber: 7S26
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Purple Night Monster
Ref: SZEN007 (7S26-03G0)
Caliber: 7S26
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Night Monster SZEN007
Ref: SZEN009 (7S26-03G0)
Caliber: 7S26
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Night Monster SZEN010
Ref: SZEN010 (7S26-03G0)
Caliber: 7S26
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 21 jewels, 41 hours of power reserve, 21,600 bph.
Second generation
In 2012 the second generation of Seiko Monster enters the scene, introducing two main innovations: the caliber 4R36 with hacking and the possibility of manual winding, and new indexes that resemble long pointed teeth.
The latest models of the second generation see the appearance of the Prospex X on the dial, which later will always be present on all models of subsequent generations.
Black Monster 2nd Gen.
Ref: SRP307 (4R36-01J0)
Caliber: 4R36
Year: 2012
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Orange Monster 2nd Gen.
Ref: SRP309 (4R36-01J0)
Caliber: 4R36
Year: 2012
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster Halloween
Ref: SRP311 (4R36-01J0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster Dracula
Ref: SRP313 (4R36-01J0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Orange/Black Monster 2nd Gen.
Ref: SRP315 (4R36-01J0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Sea Monster
Ref: SRP581 (4R36-01J0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Black Ion Monster
Ref: SRP583 (4R36-01J0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Limited Editions of the second generation
Even with the second generation, Seiko has released several Limited Editions for the Thai and Asian market, particularly sought after by collectors.
Among these editions stands out the Zamba Monster, which has a crown and indices reminiscent of the first generation.
Zamba Monster
Ref: SRP319 (4R36-01W0)
Caliber: 4R36
Year: 2012
Limited edition of 2112 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Power Blue Monster
Ref: SRP455 (4R36-02B0)
Caliber: 4R36
Year: 2013
Limited edition of 1000 pieces.
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Moon Monster
Ref: SRP457 (4R36-03B0)
Caliber: 4R36
Year: 2013
Limited edition of 1313 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Sun Monster
Ref: SRP459 (4R36-02A0)
Caliber: 4R36
Year: 2013
Limited edition of 2323 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Super Power Blue Monster
Ref: SRP461 (4R36-02P0)
Caliber: 4R36
Limited edition of 500 pieces.
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Royal Blue Monster
Ref: SRP657 (4R36-03Y0)
Caliber: 4R36
Limited edition of 1750 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Third generation
The third generation of Seiko Monsters make their debut in 2014, introducing the 6R15 automatic movement, with a power reserve of 50 hours, hacking and manual winding.
Orange Monster 3rd Gen.
Ref: SBDC023 (6R15-02X0)
Caliber: 6R15
Year: 2014
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Black Monster 3rd Gen.
Ref: SBDC025 (6R15-02X0)
Caliber: 6R15
Year: 2014
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Blue Coral Monster
Ref: SBDC067 (6R15-02X0)
Caliber: 6R15
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Ice Monster
Ref: SBDC073 (6R15-02X0)
Caliber: 6R15
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Orange Sunburst Monster
Ref: SBDC075 (6R15-02X0)
Caliber: 6R15
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Blue Monster 3rd Gen.
Ref: SZSC003 (6R15-02X0)
Caliber: 6R15
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Jade Monster
Ref: SZSC005 (6R15-02X0)
Caliber: 6R15
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 23 jewels, 50 hours of power reserve, 21,600 bph, manual winding, hacking.
Fourth generation
The latest to date is the fourth generation, which for the first time sees a downgrade of the movement compared to the previous series. In fact, from the 6R15 we’re back to the 4R36, the same caliber of the second generation.
Blue Monster 4th Gen.
Ref: SBDY033 (4R36-07N0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Black Monster 4th Gen.
Ref: SBDY035 (4R36-07N0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Blacker Monster 4th Gen.
Ref: SBDY037 (4R36-07N0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster Save The Ocean
Ref: SBDY045 (4R36-08C0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster PADI
Ref: SBDY057 (4R36-07N0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Tubbataha Reef Monster
Ref: SRPF33 (4R36-09C0)
Caliber: 4R36
Limited edition of 1000 pieces.
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Komodo Dragon Zimbe Monster
Ref: SRPF34 (4R36-09B0)
Caliber: 4R36
Limited edition of 1500 pieces.
Stainless steel case 42mm, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Yellow Monster 4th Gen.
Ref: SRPF35 (4R36-08B0)
Caliber: 4R36
Stainless steel case 42mm, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Real Thai Monster
Ref: SRPG55 (4R36-10H0)
Caliber: 4R36
Limited edition of 1991 pieces.
42mm stainless steel case, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster STO Antarctica
Ref: SBDY105 (4R36-11D0)
Caliber: 4R36
42mm stainless steel case, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster Black Series
Ref: SRPH13 (4R36-10L0)
Caliber: 4R36
Limited edition of 7000 pieces.
42mm stainless steel case, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster King Mongkut
Ref: KMITL (4R36-12M0)
Caliber: 4R36
Limited edition of 1000 pieces.
42mm stainless steel case, sapphire crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Monster STO Antarctica 2022
Ref: SBDY115 (4R36-11D0)
Caliber: 4R36
42mm stainless steel case, Hardlex crystal, screw-down crown, 24 jewels, 40 hours of power reserve, 21,600 bph, manual winding, hacking.
Summary of the models
First generation
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Black Monster | SKX779 | SKX779J1, SKX779J, SKX779K1, SKX779K2, SKX779K | 7S26-0350 | 7S26 | No |
| Orange Monster | SKX781 | SKX781J1, SKX781J, SKX781K1, SKX781K2, SKX781K | 7S26-0350 | 7S26 | No |
| Black Monster (North America) | SKXA43 | SKXA43K | 7S26-0351 | 7S26 | No |
| Orange Monster (North America) | SKXA45 | SKXA37, SKXA45K, SKXA37K | 7S26-0351 | 7S26 | No |
| Yellow Monster | SKZ203 | SKZ203K1, SKZ203K | 7S36-01B0 | 7S36 | Yes (300) |
| Blue Monster | SKZ213 | SKZ213K1, SKZ213K | 7S36-01G0 | 7S36 | Yes (1800) |
| Red Monster | SKZ243 | SKZ243K1, SKZ243K2, SKZ243K | 7S36-01B0 | 7S36 | Yes (1313) |
| Green Monster | SKZ277 | SKZ277K1, SKZ277K | 7S36-03W0 | 7S36 | Yes (1881) |
| Snow Monster | SKZ331 | SKZ331K1, SKZ331K | 7S36-05D0 | 7S36 | Yes (2555) |
Night Monsters
| Nickname | Ref | MC Ref. | Caliber | Limited |
| Orange Night Monster | SZEN001 | 7S26-03G0 | 7S26 | No |
| Night Monster | SZEN002 | 7S26-03G0 | 7S26 | No |
| White Night Monster | SZEN006 | 7S26-03G0 | 7S26 | No |
| Purple Night Monster | SZEN007 | 7S26-03G0 | 7S26 | No |
| Night Monster SZEN009 | SZEN009 | 7S26-03G0 | 7S26 | No |
| Night Monster SZEN010 | SZEN010 | 7S26-03G0 | 7S26 | No |
Second generation
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Black Monster 2nd Gen. | SRP307 | SRP307J1, SRP307J2, SRP307J, SRP307K1, SRP307K2, SRP307K | 4R36-01J0 | 4R36 | No |
| Orange Monster 2nd Gen. | SRP309 | SRP309J1, SRP309J2, SRP309J, SRP309K1, SRP309K2, SRP309K | 4R36-01J0 | 4R36 | No |
| Monster Halloween | SRP311 | SRP311J1, SRP311J2, SRP311J, SRP311K1, SRP311K2, SRP311K | 4R36-01J0 | 4R36 | No |
| Monster Dracula | SRP313 | SRP313J1, SRP313J2, SRP313J, SRP313K1, SRP313K2, SRP313K | 4R36-01J0 | 4R36 | No |
| Orange/Black Monster | SRP315 | SRP315J1, SRP315J2, SRP315J, SRP315K1, SRP315K2, SRP315K | 4R36-01J0 | 4R36 | No |
| Sea Monster | SRP581 | SRP581J1, SRP581J, SRP581K1, SRP581K | 4R36-01J0 | 4R36 | No |
| Black Ion Monster | SRP583 | SRP583J1, SRP583J, SRP583K1, SRP583K2, SRP583K | 4R36-01J0 | 4R36 | No |
| Zamba Monster | SRP319 | SRP319K1, SRP319K | 4R36-01W0 | 4R36 | Yes (2112) |
| Power Blue Monster | SRP455 | SRP455J1, SRP455J, SRP455K1, SRP455K | 4R36-02B0 | 4R36 | Yes (1000) |
| Moon Monster | SRP457 | SRP457K1, SRP457K | 4R36-03B0 | 4R36 | Yes (1313) |
| Sun Monster | SRP459 | SRP459K1, SRP459K | 4R36-02G0 | 4R36 | Yes (2323) |
| Super Power Blue Monster | SRP461 | SRP461K1, SRP461K | 4R36-02P0 | 4R36 | Yes (500) |
| Royal Blue Monster | SRP657 | SRP657K1, SRP657K | 4R36-03Y0 | 4R36 | Yes (1750) |
Third generation
| Nickname | Ref | MC Ref. | Caliber | Limited |
| Orange Monster 3rd Gen. | SBDC023 | 6R15-02X0 | 6R15 | No |
| Black Monster 3rd Gen. | SBDC025 | 6R15-02X0 | 6R15 | No |
| Blue Coral Monster | SBDC067 | 6R15-02X0 | 6R15 | No |
| Ice Monster | SBDC073 | 6R15-02X0 | 6R15 | No |
| Orange Sunburst Monster | SBDC075 | 6R15-02X0 | 6R15 | No |
| Blue Monster 3rd Gen. | SZSC003 | 6R15-02X0 | 6R15 | No |
| Jade Monster | SZSC005 | 6R15-02X0 | 6R15 | No |
Fourth generation
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Blue Monster 4th Gen. | SBDY033 | SRPD25K1, SRPD25K, SRPD25 | 4R36-07N0; 4R36-07B0 | 4R36 | No |
| Black Monster 4th Gen. | SBDY035 | SRPD27K1, SRPD27K, SRPD27 | 4R36-07N0; 4R36-07B0 | 4R36 | No |
| Blacker Monster 4th Gen. | SBDY037 | SRPD29K1, SRPD29K, SRPD29J1, SRPD29J, SRPD29 | 4R36-07N0; 4R36-07B0 | 4R36 | No |
| Monster Save The Ocean | SBDY045 | SRPE09K1, SRPE09K, SRPE09J1, SRPE09J, SRPE09 | 4R36-08C0; 4R36-07B0 | 4R36 | No |
| Monster PADI | SBDY057 | SRPE27K1, SRPE27K, SRPE27J1, SRPE27J, SRPE27 | 4R36-07N0; 4R36-07B0 | 4R36 | No |
| Tubbataha Reef Monster | SRPF33 | SRPF33K1, SRPF33K | 4R36-08C0 | 4R36 | Yes (1000) |
| Komodo Dragon Zimbe Monster | SRPF34 | SRPF34K1, SRPF34K | 4R36-09B0 | 4R36 | Yes (1500) |
| Yellow Monster 4th Gen. | SRPF35 | SRPF35K1, SRPF35K | 4R36-08B0 | 4R36 | No |
| Real Thai Monster | SRPG55 | SRPG55K1, SRPG55K | 4R36-10H0 | 4R36 | Yes (1991) |
| Monster STO Antarctica | SBDY105 | SRPG57, SRPG57K1, SRPG57K | 4R36-11D0; 4R36-11C0 | 4R36 | No |
| Monster Black Series | SRPH13 | SRPH13K1, SRPH13K | 4R36-10L0 | 4R36 | Yes (7000) |
| Monster King Mongkut | KMITL | – | 4R36-12M0 | 4R36 | Yes (1000) |
| Monster STO Antarctica 2022 | SBDY115 | SRPH75, SRPH75K1, SRPH75K | 4R36-11D0; 4R36-11C0 | 4R36 | No |
The origins: Quartz Monsters
The first Seiko watches to have a “Monster-like design” are two quartz watches, ref. SLR001 and SLR003, which were equipped with the 8F35 movement with perpetual calendar.
These two watches can be considered the grandparents of the series.
| Nickname | Ref | MC Ref. | Caliber | Limited |
| Black Quartz Monster | SLR001 | 8F35-0019 | 8F35 | No |
| Peach Quartz Monster | SLR003 | 8F35-0010 | 8F35 | No |
Series with similarities
Over the years, Seiko has introduced several series which, while not considered true Monsters, have several things in common.
Land Monsters
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Black Land Monster | SNM035 | – | 7S35-00F0 | 7S35 | No |
| Orange Land Monster | SNM037 | – | 7S35-00F0 | 7S35 | No |
| Prince Monster | SNM039 | SNM039K1, SNM039K | 7S35-00G0 | 7S35 | Yes (1666) |
Frankenmonsters (Seiko 5)
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Blue Frankenmonster | SKZ245 | SKZ245J1, SKZ245J, SKZ245K1, SKZ245K | 7S36-02S0 | 7S36 | No |
| Black Frankenmonster | SKZ247 | SKZ247J1, SKZ247J, SKZ247K1, SKZ247K | 7S36-02S0 | 7S36 | No |
| Orange Frankenmonster | SKZ249 | SKZ249J1, SKZ249J, SKZ249K1, SKZ249K | 7S36-02S0 | 7S36 | No |
| Yellow Frankenmonster | SKZ251 | SKZ251J1, SKZ251J2, SKZ251J, SKZ251K1, SKZ251K2, SKZ251K | 7S36-02S0 | 7S36 | No |
| Frankenmonster SKZ253 | SKZ253 | SKZ253J1, SKZ253J, SKZ253K1, SKZ253K | 7S36-02S0 | 7S36 | No |
| Frankenmonster SKZ255 | SKZ255 | SKZ255J1, SKZ255J2, SKZ255J, SKZ255K1, SKZ255K2, SKZ255K | 7S36-02S0 | 7S36 | No |
Trek Monsters
| Nickname | Ref | MC Ref. | Caliber | Limited |
| Trek Monster | SARB047 | 6R15-01F0 | 6R15 | No |
| Trek Monster | SARB048 | 6R15-01G0 | 6R15 | No |
| Trek Monster | SARB049 | 6R15-01H0 | 6R15 | No |
| Trek Monster | SARB053 | ? | 6R15 | Yes |
| Trek Monster | SARB055 | 6R15-01H0 | 6R15 | Yes |
| Trek Monster | SARB057 | ? | 6R15 | Yes |
| Trek Monster | SARB075 | ? | 6R15 | Yes (750) |
| Trek Monster | SARB077 | ? | 6R15 | Yes (750) |
| Trek Monster | SARB078 | ? | 6R15 | Yes (900) |
Mini Trek Monster (Seiko 5)
Ref: SRPB75
Other Ref: SRPB75K, SRPB75K1
MC Ref.: 4R36-06D0
Caliber: 4R36
Limited: Yes (1700)
Baby Monsters (Seiko 5)
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| White Baby Monster | SNZF45 | SNZF45J1, SNZF45J, SNZF45K1, SNZF45K | 7S36-03D0 | 7S36 | No |
| Black Baby Monster | SNZF47 | SNZF47J1, SNZF47J, SNZF47K1, SNZF47K | 7S36-03D0 | 7S36 | No |
| Orange Baby Monster | SNZF49 | SNZF49J1, SNZF49J, SNZF49K1, SNZF49K | 7S36-03D0 | 7S36 | No |
| Baby Monster | SNZF51 | SNZF51J1, SNZF51J, SNZF51K1, SNZF51K | 7S36-03D0 | 7S36 | No |
| Baby Monster | SNZF53 | SNZF53J1, SNZF53J, SNZF53K1, SNZF53K | 7S36-03D0 | 7S36 | No |
| Blue Baby Monster | SNZH47 | SNZH47K1, SNZH47K | 7S36-03X0 | 7S36 | Yes (999) |
| Burgundy Baby Monster | SNZH49 | SNZH49K1, SNZH49K | 7S36-03Y0 | 7S36 | Yes (1881) |
Mini Monsters (Seiko 5)
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Navy Blue Mini Monster | SRP379 | SRP379K1, SRP379K | 4R36-01K0 | 4R36 | Yes (499) |
| Snow Mini Monster | SRP481 | SRP481K1, SRP481K | 4R36-02T0 | 4R36 | No |
| Orange Mini Monster | SRP483 | SRP483K1, SRP483K, SRP483J1, SRP483J | 4R36-02T0 | 4R36 | No |
| Mini Monster | SRP485 | SRP485K1, SRP485K, SRP485J1, SRP485J | 4R36-02T0 | 4R36 | No |
| Mini Monster | SRP487 | SRP487K1, SRP487K | 4R36-02T0 | 4R36 | No |
| Mini Monster | SRP488 | SRP488K1, SRP488K | 4R36-02T0 | 4R36 | No |
| Mini Monster | SRP489 | SRP489K1, SRP489K | 4R36-02T0 | 4R36 | No |
| Mini Monster | SRP490 | SRP490K1, SRP490K | 4R36-02T0 | 4R36 | No |
| Green Mini Monster | SRP717 | SRP717K1, SRP717K | 4R36-04G0 | 4R36 | Yes (1500) |
New Monsters (Seiko 5)
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| New Monster | SRP599 | SRP599J1, SRP599J, SRP599K1, SRP599K | 4R36-03T0 | 4R36 | No |
| New Monster | SRP601 | SRP601J1, SRP601J, SRP601K1, SRP601K | 4R36-03T0 | 4R36 | No |
| New Monster | SRP603 | SRP603J1, SRP603J2, SRP603J, SRP603K1, SRP603K2, SRP603K | 4R36-03T0 | 4R36 | No |
| New Monster | SRP605 | SRP605J1, SRP605J2, SRP605J, SRP605K1, SRP605K2, SRP605K | 4R36-03T0 | 4R36 | No |
| New Monster | SRP607 | SRP607J1, SRP607J, SRP607K1, SRP607K | 4R36-03T0 | 4R36 | No |
| New Monster | SRP608 | SRP608J1, SRP608J, SRP608K1, SRP608K | 4R36-03T0 | 4R36 | No |
Baby Tuna/Monster Tuna
| Nickname | Ref | Other Ref. | MC Ref. | Caliber | Limited |
| Baby Tuna | SRP227 | SRP227J1, SRP227J, SRP227K1, SRP227K | 4R36-00V0 | 4R36 | No |
| Baby Tuna | SRP229 | SRP229J1, SRP229J, SRP229K1, SRP229K | ? | 4R36 | No |
| Baby Tuna | SRP231 | SRP231J1, SRP231J, SRP231K1, SRP231K | 4R36-00V0 | 4R36 | No |
| Baby Tuna | SRP233 | SRP233J1, SRP233J, SRP233K1, SRP233K | 4R36-00T0 | 4R36 | Yes (1300) |
| Baby Tuna | SRP234 | SRP234J1, SRP234J, SRP234K1, SRP234K | 4R36-00T0 | 4R36 | Yes (1300) |
| Baby Tuna | SRP236 | SRP236J1, SRP236J, SRP236K1, SRP236K | 4R36-00T0 | 4R36 | Yes (1300) |
| Orange Baby Tuna | SRP251 | SRP251J1, SRP251J | ? | 4R36 | ? |
| Superior Blue Baby Tuna | SRP453 | SRP453K1, SRP453K | ? | 4R36 | Yes (1300) |
| Baby Tuna | SRP637 | SRP637J1, SRP637J, SRP637K1, SRP637K2, SRP637K | 4R36-03Z0 | 4R36 | No |
| Baby Tuna | SRP639 | SRP639J1, SRP639J, SRP639K1, SRP639K2, SRP639K | 4R36-03Z0 | 4R36 | No |
| Baby Tuna | SRP641 | SRP641J1, SRP641J, SRP641K1, SRP641K | 4R36-03Z0 | 4R36 | No |
| Baby Tuna | SRP653 | SRP653J1, SRP653J, SRP653K1, SRP653K | 4R36-04D0 | 4R36 | No |
| Baby Tuna | SRP655 | SRP655J1, SRP655J, SRP655K1, SRP655K | 4R36-04D0 | 4R36 | No |
| Thailand Baby Tuna | SRP727 | SRP727K1, SRP727K | 4R36-04T0 | 4R36 | Yes (500) |
| Baby Tuna | SRPC96 | SRPC96K1, SRPC96K | ? | 4R36 | Yes (1234) |
| Rose Gold Brown Baby Tuna | SRPD14 | SRPD14K1, SRPD14K | 4R36-06X0 | 4R36 | Yes (2200) |
| Blue Butterfly Fish Baby Tuna | SRPD15 | SRPD15K1, SRPD15K | 4R36-07C0 | 4R36 | Yes (2200) |
| Baby Tuna | SRPE14 | SRPE14K1, SRPE14K | 4R36-08G0 | 4R36 | Yes (999) |
| Ice Frost Baby Tuna | SBDY053 | SBDY053J1, SBDY053J | ? | 4R36 | No |
| Baby Tuna Blue Gradient | SBDY055 | SBDY055J1, SBDY055J | 4R36-08F0 | 4R36 | No |
Summary of watch movements
Main series
| Series | Movements |
| First generation | 7S26, 7S36 |
| Second generation | 4R36 |
| Third generation | 6R15 |
| Fourth generation | 4R36 |
Other series
| Series | Movements |
| Land Monsters | 7S35 |
| Frankenmonsters | 7S36 |
| Trek Monsters | 6R15 |
| Mini Trek Monster | 4R36 |
| Baby Monsters | 7S36 |
| Mini Monsters | 4R36 |
| New Monsters | 4R36 |
| Monster Tuna | 4R36 |
Caliber 7S26
| Type | Automatic |
| Power reserve | 41 hours |
| Bph | 21,600 |
| Jewels | 21 |
| Lift Angle | 53° |
| Manual winding | No |
| Hacking | No |
Caliber 7S35
| Type | Automatic |
| Power reserve | 41 hours |
| Bph | 21,600 |
| Jewels | 23 |
| Lift Angle | 53° |
| Manual winding | No |
| Hacking | No |
Caliber 7S36
| Type | Automatic |
| Power reserve | 41 hours |
| Bph | 21,600 |
| Jewels | 23 |
| Lift Angle | 53° |
| Manual winding | No |
| Hacking | No |
Caliber 4R36
| Type | Automatic |
| Power reserve | 40 hours |
| Bph | 21,600 |
| Jewels | 24 |
| Lift Angle | 53° |
| Manual winding | Yes |
| Hacking | Yes |
Caliber 6R15
| Type | Automatic |
| Power reserve | 50 hours |
| Bph | 21,600 |
| Jewels | 23 |
| Lift Angle | 53° |
| Manual winding | Yes |
| Hacking | Yes |