The Centronic BPX65RT is a dual phototransistor module designed to detect near long-range objects. It consists of two phototransistors, one active and one passive, that operate in parallel. The active phototransistor uses a built-in red LED light source to detect motion up to a distance of 20 feet. The passive phototransistor uses ambient light to detect objects up to a distance of 6 feet. It is ideal for use in proximity sensing applications, including door and entrance alarms, line-following robots, and more.