Seiko Series 5 Automatic Green Dial with Green Nylon Band Men's Watch SRPE65K1 have the caliber number 4R36. Seiko Automatic Men's Watch. An exquisite pick for fashionable Men is this Casual Watch from Seiko. Lending you a stylish look all day long, this watch will impress you with its beautifully done with a Round shape and trendy band. This is specially designed for Men.