The Knoctify button uses a vibration sensor to detection vibrations on the surface that it is attached to. A special software is written to detect the vibration caused by knocking to trigger the button and activate the receiver light. Knock detection works best on a solid wooden surface and is not guaranteed to work on all surfaces. In some cases, when attached on the door, the button may be triggered by the opening and closing of the door as the movement of the door may be similar to a knock vibration.
Knock detection can be disabled to improve battery life. Refer to the user manual for instructions on how to disable knock detection.