Duratech Large Size Tap And Die Set, 23 Piece, Standard, Rethreading Kit For Large Size Tap Die Set: Industrial grade GCr15 bearing steel heat treated for corrosion-free performance with satisfying longevity.The thread repair set has coarse (NC) fine (NF) and national pipe (NPT) thread designations, ensuring usability in many hand threading applications. Wide Application:Create new threads or repair damaged threads on most metals like carbon steel, cast iron, aluminum, brass, copper, and stainless steel with this tap and die kit.Tip:For every full turn forward, make sure turn the tap one half back to prevent the tap from damaging. Add proper lubricant during thread cutting operation. Remove Broken Screws:This rethreading kit comes with carbon steel screw extractor, which is designed to remove broken studs, bolts, socket screws and fittings. Storage Case: Comes with blow molded case for safe keeping and makes for great transport between job locations. Complete Set Include:1tap wrench,1 die wrench,7 tap(9/16-12,5/8-11,3/4-10NC?9/16-18,5/8-18,3/4-16NF;1/4-18NPT),9 die(1/2-13,9/16-12,5/8-11,3/4-10NC;1/2-20,9/16-18,5/8-18,3/4-16NF; 1/4-18NPT)?5 screw extractor(1#(5/64), 2#(7/64),3#(5/32),4#(1/4),5#(17/64)).