Feature: Lag screws or coach screws are large wood screws. The head is typically an external hex. with the coarse threads of a wood-screw or sheet-metal-screw thread form (but larger). Lag screws are used to lag together lumber framing, to lag machinery feet to wood floors, and other carpentry applications. Great for wood, when the hex lag screw into the wood, it is very firm, it can't pull it out. If you pulled out, it will bring out the nearby wood. Note:Do not use a hammer to knock it in, otherwise, it will destroy the surrounding wood.Specification:Thread Size: M8Screw Length: 50mm/1.97inchMaterial: Carbon Steel Zinc PlatedExternal Hex Dia.: 13mm/0.51inchScrew Cap Thickness: 5mm/0.2inchColor: Silver TonePackage:25pcs x Hex Lag Screws