Visual Countdown Timer - This Round Visual Timer features a Colored Disk, make it easy to read how much time is left. Powered by Winded - This countdown timer is powered by winded, no any battery is required, solve the inconvenience of frequent battery change. Easy to Use - Just turn the Colored Disk clockwise to 55" position to wind it, then turn back to your desired time. When time is up, the alarm will ring aloud for 5 seconds. Wide Application - Compact size and colored visual disk plus loud alarm, makes it a great time management tool for classroom, home, kitchen and office, makes an excellent classroom timer, mechanical magnetic timer, study timer, toddler timer, kids timer, kitchen timer, timer clock, time tracker, and more Strong Magnetic Backing - Stick the timer on the oven, refrigerator or any other metal panel with strong magnetic backside. Product Specification - Diameter: Approx. 3"; Product Thickness: 1.26";