The SM31ELQD is an opposed-mode self-contained Photoelectric Sensor with 1 NPN and 1 PNP bipolar output. The MINI-BEAM® dc-voltage series 26952 sensor perform most reliably if it is properly aligned and securely mounted. For maximum mechanical stability, mount MINI-BEAM sensor through 18mm diameter holes by its threaded barrel or use a mounting bracket. Begin with line-of-sight positioning of the MINI-BEAM sensor to its target (all other sensing modes). It provides protection against false pulse on power-up and continuous overload or short-circuit of outputs. The reinforced thermoplastic polyester housing totally encapsulated with O-ring sealing, acrylic lenses and stainless steel screws.