Clamps Measure Current. Probes Measure Voltage. Having a Hinged Jaw Integrated into an Electrical Meter allows Technicians to Clamp The Jaws Around a Wire, Cable or Other Conductor at any Point in an Electrical System, Then Measure Current in that Circuit Without Disconnecting/De Energizing it. Beneath their Plastic Moldings, Hard Jaws Consist of Ferrite Iron and are Engineered to Detect, Concentrate and Measure The Magnetic Field Being Generated by Current as it Flows Through a Conductor. Digital AC/DC Clamp Meter | Digit Clamp Meter With Resistance | Temperature & Capacitance | Auto Ranging Digital Clamp-Meter | Trms Auto-Ranging Digital Clamp Meter .