"220V AC Cooling Fan" switching device according to the security, good flexibility, good contact when the power is turned on and off. The switch has the keys and touch-type variety. Key switch when you press a key there should not be two key phenomena connected, each key is pressed, the reset must be flexible. Timing devices require accurate timing, "220V AC Cooling Fan" rotating flexible, no jamming or friction panel phenomenon, normally open and normally closed position should be controlled and reliable. Knob, switch operation should be issued crisp sound, accurate positioning. "220V AC Cooling Fan" touch-switch touch switch command to be accurate and reliable, but requires significant difference between the stall speed, slow stall speed should be less than 70% faster document.