The Omron E3FA-TP21 is an AC input photoelectric sensor. This sensor is designed for detecting the presence of an object in environments with harsh operating conditions. It also has a long sensing distance and high noise-resistance, making it suitable for a wide range of applications. It is also highly immune to ambient light, which enables reliable operation in bright environments. Its small size, high reliability, and long sensing distance make it a great choice for a wide range of applications.