The RT250 is an electrical receptacle tester that tests the wiring conditions at an electrical outlet and inspects GFCI devices. The LCD displays the voltage, identifies the wiring fault, and the time required to trip a GFCI device. It is designated for use with North American 3-wire 120V electrical outlets. For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isn't just the name of our company, it's also our family name. And since we're an American company that's family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesn't just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857. CLEAR LCD READOUT: GFCI Receptacle Tester features a large backlit LCD readout for easy voltage reading and clear indication of wiring conditions TRIP TIME DISPLAY: LCD readout shows the time required to trip a GFCI device, allowing for quick and accurate troubleshooting DETECT COMMON WIRING FAULTS: Detect and identify common wiring faults, ensuring electrical safety and proper functionality of GFCI receptacles PATENT-PENDING OPEN NEUTRAL OPEN GROUND DETECTION: Innovative detection system identifies Open Neutral and Open Ground wiring faults, enhancing safety measures CONVENIENT AUTO-HOLD FEATURE: Auto-Hold function holds the reading for hard-to-reach outlets, providing convenience and ease of use VISIBLE LED INDICATORS: Bright green and red LEDs illuminate to provide clear visual indicators of wiring conditions, making it easy to identify issues CAT II 135V SAFETY RATING: GFCI Receptacle Tester has a CAT II 135V safety rating, ensuring reliable and safe electrical testing for various applications