GFCI Receptacle Tester Klein Tools RT210 Detects the most common wiring problems in standard and GFCI receptacles Works on GFI outlets and confirms operation of the ground fault protective device Conforms to UL Std 1436, Certified to CSA Std C22.2 #160 Built to withstand a 6.6-foot (2m) drop Operating temp: 32-degrees F to 140-degrees F (0-degrees C to 40-degrees C) Nominal Voltage: 110/125V AC at 50/60Hz in 3-wire outlet