Electrically isolated means mounted in delrin or some other non-conductive material so that the probe and the rest of machine are not electrically connected. Metal conducts electricity, and as such, cannot be used to mount the probe to the machine.

The probe itself can be anything made of metal that touches the end of the part during the machining cycle. Pictured at the top of this page is a piece of drill-rod acting as the probe, but anything made of metal can be used, including any tool which contacts the end of the part.