PS-MR9-NS2D-PHOTO SENSOR M18 R 1M NPN M12 20.The PS-MR9-NS2D-PHOTO SENSOR M18 R 1M NPN M12 20 is a small, high-performance photosensor developed for industrial accuracy. With NPN output, simple installation, and sturdy design, it's your go-to solution for dependable object detection in any situation.