Citizen Men's Eco-Drive Signature Chronograph Watch with Perpetual Calendar, BL5440-58E Case diameter : 43 mm Eco-drive is fueled by light, any light, so it never needs a battery. 1/20 second chronograph measures up to 60 minutes Perpetual calendar Dual-coated anti-reflective sapphire glass crystal. One-way rotating bezel Water resistant to 660 feet (200 M): suitable for recreational scuba diving