The Extech RD300 Refrigerant Leakage Detector detects leakages from air-conditioning units and cooling systems. It's easy to use and is ideal for detecting leakages from air-conditioning units and cooling systems that use all standard refrigerants. The multi-colored LED light bar indicates the level of leaking refrigerant detected by the RD300. The built-in, bright LED convenience light located at the sensor tip illuminates dimly lit inspection areas.