This visible movement self winding wristwatch show you the guts as it works. The beauty of it, is that it self-winds by the normal everyday movement of your arm so there is no need for a battery. It has an indefinite lifespan as when you stop wearing it, after a few days, the movement stops until you wear it again. Details: Band Width: 22mm, Clasp Type: Folding Clasp with Safety, Water Resistance Depth: Not waterproof, Dial Window Material Type: Glass, Band Length: 21.5cm, Movement: Automatic Self-Wind, luminous, Material: Stainless Steel, Dial Diameter: 44mm