Century's 13 Piece 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. Set includes: 4-40 NC; 6-32 NC; 8-32 NC; 10-24 NC; 10-32 NF; and 1/4-20 NC taps, #35, #7, #21, #25, #29, and #43 drills, and a 0"-1/4" t-handle tap wrench.