Supplied with 2 standard sensor, however sometimes a larger sensor may be required. In the product description you will find the maximum diameter of the cable the sensor will fit. It is a good idea to check this before ordering. One important rule to remember is the sensor must not be too tight as this can crack the magnets inside the sensor. If your cable is very close to the maximum, choose a larger sensor. It does not matter if the sensor is loose on the cable.