The Whisper Transmitter is an accessory that is used with the Whisper Ultrasonic Leak Detector to locate leaks in walk in coolers, freezers, wall and ceiling joints, around doors, windows, body seals, rubber moldings, and ducts. The Transmitter produces the exact frequency of ultrasound (40.5 kHz) as received by the Whisper. Therefore, by placing the Transmitter in a sealed area, and scanning the exterior of this area, any signal escaping from the sealed area will be indicated by a reading on the Whisper. A flaw in the seal can quickly and accurately be located and pinpointed.