Size details: Dial diameter: 1.65 inches / 42 mm Dial thickness: 0.47 inches / 12 mm strap Width: 0.78 inches / 20 mm Belt length: 8.7 inches / 220 mm Table weight: 115g Material type: artificial sapphire glass (scratch resistant) 100M waterproof: Suitable for snorkeling and swimming, but also enough for daily use Seiko movement: Japanese NH35A movement, long service life Material type: all stainless steel strap with hidden buttons (function(f) {var _np=(window.P._namespace("AplusModule"));if(_np.guardFatal){_np.guardFatal(f)(_np);}else{f(_np);}}(function(P) { // register javascript with unique module id P.when("jQuery", "AplusModules-module-6", "ready").execute(function($, hoverModule) { hoverModule("aplus-module-6-1"); }); })); What if the watch stops? The fully tightened spring needs to turn the crown clockwise 20 to 30 times to start the watch and provide backup power. A watch with automatic winding function needs to be used once a day (about 8 to 12 hours a day), The winding of a self-winding watch is performed by twisting the movement of the arm, and due to the action of the rotor, The device uses the natural movement of the wrist to automatically wind the stringed instrument by rotating the counterweight. If the automatic watch is not aligned within a day or two, or the natural movement of the wrist is small, it will gradually go downhill and require manual winding to start again. Turn the crown spring on the ratchet to tighten the spring to save energy, and then manually store it in the mainspring. After pulling the crown out a short distance, you can turn the hands to set the watch. 1662 1639 1644 1645 1651 Waterproof 100M 100M 100M 100M 100M Movement Automatic Automatic Automatic Stainless steel Automatic Strap material Stainless steel Stainless steel Stainless steel Stainless steel Stainless steel Bezel material Aluminum Ceramics Ceramics Stainless steel Ceramics