PS-RL4-NS22-PHOTO SENSOR STD RT 4.2M NPN TEACH 2M 20.The PS-RL4-NS22-PHOTO SENSOR is a durable and dependable photoelectric sensor with a 4.2-meter range and NPN output. It is ideal for industrial automation, including manufacturing, packing, and safety applications, and comes with a teach function for simple setup and a 2-meter connection for easy installation.