The FastenMaster FMTLOK06-250 TimberLOK is a heavy-duty wood screw for applications such as attaching rafter or trusses to the top plate, landscape timbers, fences, decks, headers, stair stringers and more. TimberLOK replaces 3/8-inch lag screws and is approved for use in ACQ pressure treated lumber. There is no need to predrill with TimberLOK. Its sharp point and aggressive threads zip right into the densest woods. A 6-inch TimberLOK is a code-compliant way to attach rafters or trusses to a double top plate. TimberLOK is tested and supported by engineering data that conforms to the most current ICC standards. It is also approved for use in ACQ or treated lumber.