How to use: Turn the timer clockwise once to zero, then turn it back to the desired time, for example 5 minutes , 10 minutes, and the timer will ring a clear bell. Ring time 3-5 seconds An error of 1-2 minutes is normal. Features: Ribs take half an hour to cook, crab takes ten minutes to steam, and the milk is hot in five minutes. It would be nice if you could always remember that the time is up when you are busy in the kitchen. These little timers can help you, you don't have to worry about boiling dry hot vegetables anymore. Half an hour is enough for a nap, 20 minutes of hair oil, half an hour for the child to complete a set of math exercises, 20 minutes to memorize English words, and at least half an hour for exercising in the morning.