This Glassbreak Sensor detects in a full 360-degree coverage pattern, with a maximum 25-foot (7.5m) radius from sensor to glass. Using patented Pattern Recognition Technology, the sensor listens for actual patterns of breaking glass while eliminating most false alarm patterns. The Sensor listens across the glassbreak frequency spectrum for greater false alarm immunity. In independent lab tests, the Sensor"s technology provides 25 percent better false alarm immunity than industry leading glassbreak sensors. The Sensor can be tested without opening the unit by activating a handheld glassbreak tester at close range. A simple hand clap feature lets you confirm at any time that the Sensor is powered up.