It is another amazing design Automatic Mechanical Self-winding mechanism and high quality Brand Magnetic clasp. The cashback is see-through design. Dial Window Material: Resistant-scratch Mineral Glass, Automatic Mechanical Self-winding mechanism and high quality Brand Magnetic clasp. A Fully automatic mechanical Analog watch, relying on the motion of the arm and automatic winding, so must wear more than 8 hours a day to ensure timely and accurate. Mechanical watches should be Kept away from television, computers and other things with magnetic fields, so as not to affect the watch work. Precise Movement with the latest breakthrough Patented Mechanical Technology. – Composed with Tiny  This is a mechanical watch, Power by winding spring manually or self-winding(no need battery).