is a ribbed feature lodged at the end of the lower thread of a DT screw. Its function is to shear off sharp steel protruding from the sheet so that the protective coating at the shank of the DT screws does not become damaged. It prolongs the lifespan of a screw by up to 40%.

With corrosion resistance as our main concern, we have incorporated feature on all our DT (Double Thread) range. DT screws are mounted on the crest of the steel roofing profile. As such, the hollow portion between the crest and the steel structure is an area where moisture is trapped. And during a hot weather, this moisture acts as a corrosive agent compromising the integrity of the protective coating. Without the feature, the steel that was sheared off due to the initial penetration of the drill tip would have scratched the protective coating. With knife like sharpness, the protective coating would then be inevitably scratched off and the raw base steel of the screws would be exposed. This scratched portion would then be exposed to all contaminants and high humidity, hence drastically shortening the life span of the fasteners.