The Retrotec DucTester is designed specifically to measure residential duct leakage. It is used to locate duct leaks and to measure the results of duct sealing. The DucTester can also be used in conjunction with a blower door to neutralize duct leaks to indoors so that only duct leakage to outdoors is measured. DU 200 Duct testing system includes a calibrated fan, a digital dual-channel pressure gauge, and a Flex Duct with flange to attach the fan to a register. Systems also include a hard-sided fan case, an AC adaptor for the gauge, and a roll of Grill Mask.