The Hands free interface fits exactly with all generations of the existing "Audio-tactile pedestrian detector (ATPD)'. The hands free interface is opperated by a PCB with intergrated dual PIR sensors and a single Fresnel lens that focuses the signals into the sensors, should one fail he other acts as a back up.
The housing has been made tamper proof through hidden seams, a cast aluminium body, vandal proof fittings and no hidden edges.