Infrared Home Defender - motion detecor alarm for home or business. Can be set to alarm or chime. Position around room/household entrances. Protects a designated area. Triggered when the invisible PIR protected zone is breached. Doberman is proud to offer the PIR Sensor Alarm. This unit can be placed anywhere or mounted on the wall or ceiling. Using Passive Infrared (PIR) technology, this alarm unit can designate a protected zone up to 15 feet in a 90 degree sweep from the device. If an intruder trespasses into the invisible protected zone, PIR motion detection triggers the loud alarm.