FAAC XP 20B D Surface-Mounted Adjustable Photocells 20M B - System with 24V Wired Power Supply for Transmitter and Receiver. Model 785 102. The new XP 20 D adjustable photocells consist of a transmitter and receiver with modulated infrared beams, with a range of up to 20 m. When the light beam is blocked, the receiver changes position. The new XP 20 D photocells can also be wall-mounted using a column. This column allows for mechanical adjustment of the beam axis, up to 180° horizontally (-90°, +90°). These new photocells also feature vertical optical self-alignment, particularly useful on uneven surfaces. The XP 20 D has compact and ideal dimensions of 41 x 130 x 42 mm. The 16 mm housing can contain unwanted cables both at the rear of the device and in its lower section. TECHNICAL SPECIFICATIONS Model: XP.