Thread: Coarse / Thread / Alloy Steel / Black Oxide Recommended Hex Socket Allen Key Wrench: 5/64 (Inch) Thread Diameter-Pitch: 8-32, Length: 1/4 inch Recommended Hex Socket (Allen Wrench) Size: 5/64 (Inch) Black Oxide is not a protective finish and will rust if exposed to moisture. Stainless Steel material is recommended for environments with moisture Cup point Set Screws are headless screws whch are threaded the entire length. They have an internal hexagonal drive at one end and a cup-shaped indentation at the other end. The cup point is the most popular style set screw. Designed for fast, permanent and semi-permanent location of parts on shafts with hardness differential of 10-15 Rockwell C points and where cutting in of cup edge on the shaft is acceptable.