This range of probes are suitable for use as a speed sensor for Terratrip or other types of trip meters / rally computers.There are 4 different options available - Standard Wheel Probe - This universal sensor reads the speed from a bolt head on a hub, usually on an undriven wheel. Two versions are available. One which requires a maximum of a 2mm gap to operate and one which requires a maximum of a 4mm gap. Universal Speedometer Probe - Designed for use with any car which has a mechanically driven speedometer. Gearbox Probe - Suitable for most Japanese cars with a mechanically driven speedometer. This probe screw onto the gearbox and accepts the speedometer cable. Dual Sensor Interface - For cars with an electronic speedometer. This interface allows both the original speedometer and one other device to be driven from the original gearbox sensor.