The AIM Infrared Receiver sometimes referred to as an Optical Lap Receiver, installed on a race car / bike or kart, receives the lap signal from the infrared transmitter positioned at the side of the track. It is available with a 4-pin 712 (metal screw on) or a 4-pin 719 (plastic) connector and just needs to be pointed to the side of the track where the transmitter is installed to see it.The car infrared receiver has a 300cm lead, the bike sensors have 90cm leads and the kart sensors have 140cm leads, although there is nothing to stop you using the lead which suits your length requirements the best.As a guide, the 4 pin 712 (metal screw on) connector is used with;EVO4S, EVO4MyChron5, MyChron5 2T, MyChron4, MyChron4 2Tand the 4 pin 719 (plastic) connector is used with;EVO5MXL2MXG, MXS, MXP (MX Series)