3/8-16X3 Unslotted Indented Hex Washer Thread Cutting Screw Type F Fully Threaded Zinc An 300 pcs

3/8-16X3 Unslotted Indented Hex Washer Thread Cutting Screw Type F Fully Threaded Zinc. Thread-Cutting Type-F threaded screws are used in heavy gauge sheet metal, aluminum, zinc and lead die castings, cast iron, brass and plastic. In stainless steel, material into which the screw is to cut threads should have a lower hardness by 10-20 Rockwell hardness. Indented hex washer head offers advantages of hex head, plus greater protection to mating surface.