The SICK WT9-2P430 is a compact, self-contained through-beam photoelectric sensor from the robust WT9 series. It integrates both the transmitter (emitter) and receiver into a single, unified housing, creating a precise "optical fork" or "U-channel" for detection. Objects are detected the moment they break the infrared light beam traveling directly between the built-in emitter and receiver. This design offers the high reliability of a through-beam system in an extremely compact and easy-to-install format.