2Pcs Infrared Beam Detector Burglar Alarm Sensor Automatic Door Light Sensor Alarm System Single beam infrared radiation: suitable for anti-theft applications such as doors, windows, boxes, fences, and more Compact size with effective performance Sealed shell design for enhanced waterproof capability: withstands various weather conditions to protect internal components from rain damage Detection distance up to 20 meters: ensure proper alignment of emitter and receiver on the same horizontal line during installation Stable and reliable anti-interference performance: features a hemispherical optical lens for concentrated, precise beam transmission without scattering; built-in automatic strong light adjustment system helps reduce interference from bright ambient light or vehicle headlights Specifications: Light source mode: Infrared pulse type Detection method: Beam interruption type Package Includes: 2 Pcs Infrared Beam Detectors Note: Slight measurement variations of 2-4 cm may occur due to different measuring methods; kindly understand