3 & ASME B1. Size: 1/4 inch-28 X 1 inchPan Head, Phillips DriveUse with nuts or pre-threaded holes of the same diameter & thread sizeOften used in machinery & appliancesNuts and washers not includedThread Type: Fine, Thread Class: UNF-2A, Point Style: BluntSpecification(s) Met: ASME B18.6.1.