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(9/16-12,5/8-11,3/4-10 NC；9/16-18,5/8-18,3/4-16 NF; 1/4-18 NPT), 9 die(1/2-13,9/16-12,5/8-11,3/4-10 NC; 1/2-20,9/16-18,5/8-18,3/4-16 NF; 1/4-18 NPT)，5 screw extractor(1#(5/64), 2#(7/64),3#(5/32),4#(1/4),5#(17/64))