SECO-LARM E-960-D190Q Enforcer Twin Photobeam Detectors with Laser Beam Alignment, 190' Outdoor/390' Indoor Sensing Range, Non-polarized Power Onputs, Pack of 1 Including 2 Detectors Built-in laser beam alignment system speeds accurate,reliable positioning Twin infrared beams provide reliable perimeter security, minimizing false alarms from falling leaves,birds, etc. Lensed optics reinforce beam strength & provide excellent immunity to false alarms due to rain, snow,mist, etc. Weatherproof, sunlight-filtering case for indoor &outdoor use Anti-frost system so that beam functions even inextreme conditions