Seiko 1520-3680 Watch Guide The Seiko 1520-3680 is a watch model based on the 1520 movement.Caliber 1520Other models with the same movement1520-31101520-33001520-33011520-33101520-33311520-33321520-33371520-35701520-35801520-36101520-36301520-36601520-366A1520-366G1520-36701520-367A1520-36891520-36901520-37001520-37101520-50001520-50091520-5010
