CITIZEN's Promaster Diver is the perfect ISO compliant timepiece for the bold seeking the thrill of a deep-sea challenge. Built with diving in mind, this timepiece is tough and durable. The Promaster Diver, shown in stainless steel with diamond-like carbon coating, features a helium release valve, a one-way rotating elapsed-time bezel, a screw-back case and screw-down crown, and an anti-reflective crystal. Water resistant up to 300 metres. Case size 48 mm.