The Harmony wireless and batteryless push button range enables remote control of a relay (receiver) by means of a push button (transmitter). Control is by radio transmission. The transmitter is fitted with a "dynamo" type generator that converts the mechanical energy to electrical energy when the push button is pressed. A radio-encoded message with a unique ID code is sent to the receiver several dozen meters away. One receiver can be actuated by several different transmitters. Push Button Transmitter and Receiver Kit