Analog clamp meters have iron jaws coated in plastic that clamp around conductors, wires, and cables to detect and measure electrical currents. These electrical signals cause the indicator needle to move back and forth across a scale marked with units of measure to specify readings. These portable and handheld instruments are used for testing, troubleshooting, and diagnosing industrial and electrical equipment in general repair and maintenance applications. Select meters have ports that accommodate leads for additional testing capability. Unlike some digital units, analog clamp meters will not freeze up in severe hot or cold environments.