Socket Set Screw, Cup, 3/8 in Overall Length, 5/16-24, Alloy Steel, Black Oxide, PK 100/ THREAD CLASS: 3A THREAD DIRECTION: RIGHT-HAND FASTENER LENGTH: 0.375 INCHES NOMINAL HEAD STYLE: C101 HEADLESS (SETSCREW) POINT DIAMETER: 0.156 INCHES MINIMUM AND 0.172 INCHES MAXIMUM POINT STYLE: F12 CUP INTERNAL DRIVE STYLE: D5 HEXAGON NOMINAL THREAD DIAMETER: 0.312 INCHES WIDTH ACROSS FLATS: 0.156 INCHES NOMINAL THREAD QUANTITY PER INCH: 24 HARDNESS RATING: 45.0 ROCKWELL C MINIMUM OVERALL AND 53.0 ROCKWELL C MAXIMUM MATERIAL: STEEL OVERALL THREAD SERIES DESIGNATOR: UNF