The WTB4S-3P2231 is a photoelectric sensor manufactured by Sick. It is a miniature rectangular device, measuring 40 x 40 x 14.3 mm, and it is designed for fast and accurate detection of small parts and products. It can be used with a variety of target materials, and it has a detection range of up to 5 meters. It also has a high switching frequency of 25 kHz and can be used with both normally open and normally closed contacts. The sensor also has an LED on its face, which indicates power supply, target detection, and diagnostic functions.