The Door-Safe™ WT tester kit consists of 2 units, an ultrasonic transmitter unit and a portable, hand-held receiver unit connected to a flexible inspection microphone and hard-hat compatible headphones. The transmitter and receiver are each supplied in protective leather cases fitted with neck straps to allow for hands-free use. The complete Door-Safe™ kit is contained in a blue plastic foam-lined carry case for easy transportation and storage.

If ultrasound can pass through the door or hatch seals, then it is also true that water may be able to pass through. The Door-Safe™ transmitter generates ultrasound on one side of the door or hatch and the receiver unit on the other side of the door tries to detect any ultrasound. If none can be detected the door is water-tight. Any ultrasound that has leaked through is shown on the receiver unit in decibels on the digital LCD display and also converted to an audible sound, which can be heard through the headphones. The size of the problem can also be established from the strength of the signal displayed in the universal requirement of decibels.