HeadLOK is a heavy duty structural wood screw that is ideal for many wood applications including deck framing, stair stringers, attaching rigid foam (SIPs), fences, kitchen cabinets and more. The HeadLOK flat head fastener requires no predrilling and offers higher design shear than 3/8" lag screws. The SpiderDrive™ System contains 8 points of contact, maximizing bit fit and reducing stripping. HeadLOK zips right in and creates a great finished look.