When leaks occur they often generate an ultrasonic frequency that is beyond human hearing. Amprobe?s TMULD-300 converts these sounds into an audible range for easy detection. The TMULD-300 tests pressurized air lines, refrigeration systems, and steam lines for leaks. Quickly and easily locate a leak location with this unique device. The TMULD-300 includes an ultrasonic transmitter that is great to use in areas where leaking gases are not sufficiently pressurized. Check for door or trunk seals, windshield leaks. The transmitter creates ultrasonic sound waves for detecting cracks and leaks.