SCRATCHSHIELD This patented unique feature reduces damages to fastener shank and increases the lifespan of the fastener and prolongs the sustainability of the fixtures.   SCRATCHSHIELD is a ribbed feature lodged at the end of the lower thread of a double-threaded fastener. It is to remove burrs on the roofing sheet created during the initial drilling. Thus the protective coating on the shank does not become damaged. It prolongs the lifespan of a long length fastener by up to 40%. With corrosion resistance as our main concern, we have incorporated SCRATCHSHIELD on all our double threaded fasteners of length 35 mm or more.   Such fasteners are designed for crest fixing of roofing sheets. As such the hollow space between the crest and the immediate layer is an area where humidity is high. Especially during hot weather, the moisture in a humid environment acts a corrosive agent compromising the integrity of the protective coating.   Without SCRATCHSHIELD, the burr from the roofing sheet created during the initial drilling would have scratched the protective coating. With a knife-like sharpness, the protective coating would then be inevitably be scratched off and the steel will be stripped bare of its protection and be exposed to all contaminants and high humidity, hence drastically shortening the lifespan of the fastener.