The Mag Probe Sept 1, 2016 The Non-Contact Bartol Mag-Probe is a Magnetic Field Detector that will help you test Electrical Solenoid Valves, Relays and Coils in seconds. This Magnetic Field Detector is manufactured with components designed to last a long time and are designed with intrinsically safe performance in mind. The components are epoxy sealed inside a durable plastic housing featuring a hermetically sealed sensing device. There are no exposed contacts capable of generating a spark and the electrical signal operates on only 6 volts DC and is very current limited. David Posey Chief Technology Officer HSI Sensing, Chickasha, OK