Tapping Screws, Self-Tapping Screws or Sheet Metal Screws create their own mating thread in pre-drilled holes. Type A and AB are the more typical sheet metal screws with a fairly sharp point. The Type A tapping screws have wider spaced threads for self-starting in thin metal or resin filled plywood. Type AB self-tapping screws have more threads per inch that are used in brittle material. Type B tapping screws have a blunt end that are best suited for thru-holes in plastics, thin metal, and non-ferrous materials. JM Hardware® Tapping Screws have round heads and have multiple starting threads.Sheet metal screws are designed for connecting thinner metal objects to one another or connecting metal to wood, plastic, and other materials. Many can start their own pilot hole.