Widely used in electric hand drill or other power tools.
Great to replace the old or broken one of your drill.
Speed is convenient to adjust, press down the switch button to start, the lower you press down, the faster the speed is.
NOTE:
Some common signs of a broken or failing switch are: Tool has completely stopped functioning - it will not turn on. Tool operates intermittently, requiring multiple tries to turn on, until eventually it will not turn on at all.