Bulova Men's watch 98G56Powered by your arms motion ( the swinging of one's arm causes a micro-generator to spin producing electrical energy which is stored in a rechargeable power cell. Fully charged watch runs for over two months without further motion. No battery replacement ever needed. Open back view of oscillating movement. Stainless steel case and bracelet. Domed crystal. Date window. White patterned dial. Uni-directional rotating bezel. Luminous hands and hour markers, Screw back. Fold-over buckle / safety clasp. Water resistant to 100 meters / 330 feet. Case measures 40mm diameter by 13mm thick 2 years original manufacturer warranty.