Glass break simulator, for testing acoustic glass break detectors GS04, BMG04, 9001GM, 9000GMD, 9001PG, 8005B, 8000PB, 6000GM. Reacts to changes in air pressure that occur when pressure is applied to a pane of glass. A sound like breaking glass is then automatically generated. Power supply: 9 volt block battery (included). Dimensions: 70 x 135 x 29mm.