MS51021 Cup Point Hex Socket Set Screw, Corrosion resisting (Chrome-Nickel) Steel, Passivated and Self Locking (S/S By NASM51021, 29 DEC 1972). Socket Set Screws come in different types and sizes including: AN565, MS18063, MS18064, MS51021, MS51023, MS51029, MS51031, MS51038, MS51045, MS51963, MS51964, MS51965, MS51966, NAS1081. MS51021C, MILITARY STANDARD, SETSCREW-HEXAGON SOCKET, CUP POINT, CORROSION RESISTING (CHROME-NICKEL) STEEL, PASSIVATED, UNC-3A PLAIN AND SELF LOCKING (29 DEC 1972) [S/S BY NASM51021]