Ideal Security Inc. SK623 Wireless Garage Door Alert "Transmitter detects when garage door is open and will send wireless signal to trigger receiver and activates alert Set includes 1 garage door sensor, one receiver/alert and one remote control 3 ""C"", 2 CR2032 3V batteries and adapter included Water resistant transmitter Receiver features 6 sounds for optional and easily distinguishable sensor detection Receiver compatible with up to 6 additional wireless sensors (contact, motion sensors, siren and additional remote controls) Wireless RF transmission distance 30-40 meters Links with Ideal's wireless telephone diallers (SK618, SK633, SK634 and SK642) This unit can be converted to siren rather than an alert with Ideal SK626"