Citizen Eco-Drive Radio-Controlled Chronograph World Timer; Atomic time in 26 world cities; radio-controlled accuracy in 5 zones. 1/20 second Chrono measures up to 60 minutes, perpetual calendar, 12/24 hour time, power reserve, non-reflective sapphire crystal. Stainless steel with black ion plating. Featuring our Eco-Drive technology – powered by light, any light. Never needs a battery. Caliber number H800.