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 in 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 in to the densest woods.