Citizen Watch Promaster Diver Eco Drive Mens. Proof that a dive watch can be fun and functional with the Citizen ISO-compliant Promaster Diver. With Eco-Drive technology, it is powered by light and never needs a battery, so you'll never need to open your caseback making sure your watch maintains it factory sealed and water resistant. Featuring Citizen Eco-Drive technology?powered by light, any light. Never needs a battery.