The Seiko Men's 5 Automatic Silver Dial Stainless Steel Watch boasts high-tech Japanese automatic movement hidden behind classic analog styling. Precise 21-jewel Japanese automatic movement keeps this watch functioning without a battery: It is powered automatically with the movement of your arm. Details Model: SNK355K1 Movement: Automatic 21-jewel Power Reserve: Approximately 41 hours Case Material: Stainless Steel Case Size: 38 mm Dial: Silver with luminous silver-tone hands & markers Crystal: Scratch resistant Hardlex Crystal Strap Material: Stainless Steel Lug Size: 20 mm Water Resistanct: 30 meters/99 feet