Seco-Larm E-931CS22RRCQ Enforcer NIR Retro-Reflective Entry Alert System (2 Pack), Up to 22 ft. (7m) Sensing Range, Speaker Volume Can Be Adjusted or&nbsp;Turned Off, 9VDC Adapter Included Perfect for monitoring an entrance or use as anentrance indicator Will make "ding-dong" sound or siren sound when the beamis interrupted When in siren mode, sounding time is adjustable from 3 to30 sec. All components plug into each other. No hard wiring required. 32ft Cable from speakerto sensor Includes the following: NIR retro-reflective sensor, Reflector, Speaker, 9VDC 200mA power adapter,6ft cable