These Circuit Testers feature an extra long wire that stretches up to 12 feet for use, then automatically retracts. Quickly and easily check electrical circuits and accessories on 6 and 12 volt systems. Great for use on cars, trucks, boats, trailers, motorcycles, airplanes and snowmobiles. Super sharp probe. A heavy-duty ground clip with insulator is on one end of the retractable wire and a spring supported strain relief is on the other. The bulb is easily replaced.