Sheet-metal screws were originally designed for metal, like for use in a B-Vent Pipe, but can be used for a number of other applications too. They can be used with plastics, rubber, or plywood. Regardless of the material, the driving point needs to be larger than the depth of the material being driven into. Without a long enough drive point, the threads will contact the materials before the hole is adequately bored, and the screw will snap.
