The Orbit Max High Flow Mechanical Tap Timer works just like an egg timer. Twist the dial to the desired watering duration up to 120 minutes and the timer will turn itself off. The mechanical operation requires no batteries and makes this one of the easiest and quickest timers to use.  It has a large dial with both timed watering and manual watering options. Timed watering can be set from 15 to 120 minutes.