Testo 750-3 Digital Voltage GFCI Phase Rotation Meter with LCD Display meets CAT III 1000 V CAT IV 600 V safety standards while testing low input impedance, phase sequences, voltage, GFCI outlets, single probe voltage,, and continuity. The Testo 750-3 features an innovative design where you can see the LED voltage bar indicator from almost any angle and a built-in flashlight for dark environments.