Threads change direction to cut into composites and push material back into the hole to prevent distorting the surface around the hole. Also known as trim-head deck screws, these have a small flat head and slender shank to reduce the risk of splitting. They have a Type 17 auger point to penetrate softwood and plastic-wood composite decking material. A Torx drive allows you to apply extra force with less slippage or damage to the recess. Made from 18-8 stainless steel, they have good chemical resistance and are a good choice for ACQ-treated (arsenic-free) lumber. They may be mildly magnetic. Length is measured from the top of the head.

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