This includes what is said to be the most popular photoelectric sensor in the market, the S51 series. With through-beam, retro-reflective, polarized retro-reflective and diffuse modes, S51 sensors are well-suited for applications in all industries including packaging, bottling and material handling. Unlike other 18mm sensors, S51 sensors have a flat cylindrical housing that offers numerous mounting choices. The S51 series is well-suited for harsh industrial environments, with a rugged housing and IP67 mechanical protection. All S51 sensors feature a sensitivity adjustment potentiometer that can be easily adjusted for accurate, precise and reliable detection.