This is an great example of aCitizen Promaster Titanium Divers watch. It needs a new battery (pressure test done at the same time) battery last changed 3 1/2 years ago. The following details are on the back "Stainless Citizen Watch Co. 3740-H17575 Y GN-4-S Japan ".
Bold, sporty and lightweight, this Citizen men's chronograph watch features a round blue dial, with luminous hands and hour markers, and date window between 4 and 5 o'clock positions. All of these are framed in a titanium case, push crown and scratch resistant sapphire crystal.
Citizen Perpetual Calendar AT4010-50E 42mm Silver Titanium Bracelet & Case Anti-Reflective Sapphire Men's Watch. Atomic Timekeeping - The Most Accurate Watch in the World. Perpetual Calendar. Radio Controlled in 5 Time Zones.