1. wind up timer is mechanical and needs to be wound up. If you do not follow the instructions, the timer will not sound when the time is over. For example, it takes 5 minutes to boil an egg. In the first step, you need to turn the timer clockwise, from 0-5-10-15 to 20-30-40-55. Note :(the hands end at 55 minutes) step 2: turn the timer counterclockwise from 55-40-30-20-15-10-5. Note :(the pointer ends at 5 minutes). Step 3: After 5 minutes, the timer will sound. 2. Instructions must be read before use, screwing directly to the desired minute will not ring because the mainspring is not screwed.The egg timer is mechanical and has a wind-up sound when used. According to the instructions, when the time is over, the ring time is 3-5 seconds 3. wind up timer is made of high-quality stainless steel, which is durable and not easy to rust and he timer is well built, accurate, (easy to clean, too). 4. wind up timer can use to Arrange children play times, time outs, bath times, and while we cook together. It makes things a bit more fun and also help children know the value of time. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.