Seiko W851-4040 Watch Guide The Seiko W851-4040 is a watch model based on the W851 movement.Parts List4HV11Bband - bandW85110others - machine codeW8514040N2Aothers - caseOther models with the same movementW851-4000W851-4010W851-4020W851-402AW851-4030W851-4070