The Robinair Tracer Gas Leak Detector Service Kit, No. LD9-TGKIT, with sensor technology is designed to detect a 5 percent hydrogen / 95 percent nitrogen tracer gas mixture. The detector's full color liquid crystal display (LCD) and sweep mode function convey messages, graphics, and prompts to help technicians locate the source of a leak. A patented three LED inspection light aids in locating and inspecting suspected leak sources. According to the company, filling a system with tracer gas is quick and effective, with a lower cost than refrigerant. The kit detects leaks as small as 0.5 oz. per year for R-134a and .015 oz. per year for R-1234yf refrigerant.