You must remember to turn it off manually with side switch after every use. This a very nice little timer, does not come with a battery, but you can put an AA battery in easily, and it works well. The biggest problem with this timer is that it does not automatically shut off after any use whatsoever. You have to be sure to flip the little side switch, or it runs down the battery. Remembering to flip the switch is difficult, as all the timers I have ever used have an auto off after use. So if you can remember to manually switch it off, great - if you forget or don't realize it needs to be manually turned off, good luck!