Eddy current probes are supplied with 1 m of integral cable, which can be extended to 9 m (by the addition of up to 8 m of extension cable). However, long cables will often give installation problems as they need to be rotated during the gap set-up process; in which case screw-on extension cables are recommended. However, once a system has been manufactured and calibrated with an extended cable it can only be exchanged or renewed with one of equal length and the system will require recalibration.