Modern-Electronics m-e 41021 radio bell transmitter

For the wireless extension of your doorbell, place the active transmitter next to the existing doorbell. Once it rings, the wirelessly connected receiver is activated. This is ideal for wirelessly extending existing doorbells. The sensitivity of the response is infinitely adjustable. The wireless range depends on the receiver used and can reach up to 200 meters in open fields. It also works with telephones. There are indicator lights for battery and transmission functions.