6. Size: #2-56 X 1/4 inchRound Head, Phillips/Slotted Combination DriveUse with nuts or pre-threaded holes of the same diameter & thread sizeOften used in machinery & appliancesNuts and washers not includedThread Type: Coarse, Thread Class: UNC-2A, Point Style: BluntSpecification(s) Met: ASME B18.Machine Screw, Round, Phil/Sltd Comb Drive #2-56 X 1/4in Zinc Plated Steel 100PK They are frequently used in machinery and appliances.3 & SAE J82.