Measures Watts, Current, and Voltage. The compact Extech 380940 is a 400 Amp mini True RMS AC/DC power clamp meter with a small diameter jaw designed to reach in small areas while providing power calculations up to 240kW. With the added convenience of instant watt readings, a feature normally reserved for full-size meters, this mini power clamp is useful for essential troubleshooting tasks in plant maintenance, electrical, HVAC, and telecom work, as well as residential electrical repairs, energy audits, fleet maintenance, marine, and motorcycle repair. Complete with test leads, 2 AA batteries, and carrying case.