The TBG heavy duty truck bed screw is perfect for fixing timber to steel frames. It has a countersunk ribbed flat head, self tapping thread and drill point with wings. The wings ream a hole larger in the timber and break off when they hit the steel. This allows the timber to be pulled tight to the steel. Suitable for fixing to steel up to 5mm thick. TBG screws are suitable for all types of timber including Keruing hardwood and WISA plywood. They are also mechanically galvanised and so are suitable for outdoor use.