Hex head lag bolts are also called lag screws and are recommended for all types of wood or metal to wood construction where standard wood or deck screws are too short or light and where nails or spikes lack sufficient strength. They can be installed in wood with pre-drilled pilot holes or in masonry with lag shields. In wood to wood applications the non-threaded shank allows the second piece to be drawn tightly to the first piece of wood. Use flat or fender washers to provide a larger bearing surface and to prevent the head of the lag bolt from imbedding in the wood. Bare finish fasteners have very low corrosion resistance. This is a good choice for indoor use or when protection from the elements is not an issue. Use hot dipped galvanized or 18.8 stainless steel for outdoor projects or where corrosion is of concern.