Coach screws, also commonly known as lag bolts or lag screws, are a heavy-duty wood screw used mainly in timber to timber construction. Coach screws have a hexagon head for easy insertion in high torque applications. Coach screws are manufactured from mild steel to allow for movement in the timbers over time and ensures the screw will bend with the timbers and not shear. Coach screws are also commonly used for fixing metal plates or concrete posts to timber, and work well when fitted into masonry with a nylon plug.