Techko Maid Door Knob Hanger Vibration Sensor Alarm and Chime: * Detects vibration from attempted door entry * High output 100-110 dB 6-tone alarm * Alarm/Off/Chime slide switch operation * Built-in siren or chime modes * Alarm activation delay for silent setup * No tool installation * Ultra-slim design * 3 x 1.5V AAA batteries operation (included)