Century's 12 Piece Machine Screw and Fractional Tap & Drill Set features precision cut threads, accurately formed for consistent, exact threading. Heat treated and tempered for file hard threads, and longer, useful life. Desgiend for hand cutting applications. Dies are 5/8" across the flats. Set includes: 6-32 NC, 8-32 NC, 10-24 NC, and 10-32 NF machine screw plug taps and dies, 1/4-20 NC fractional plug tap and die, 5/8" die stock, and 0"-1/4" t-handle tap wrench.