^^6 Piece High Speed Steel NPT Pipe Tap Set^^ 1/8'^^ 1/4'^^ 3/8'^^ 1/2'^^ 3/4' and 1' in Wooden Case^^ DWTHS1/8-1SET^^6 Piece High Speed Steel NPT Pipe Tap Set^^ 1/8'^^ 1/4'^^ 3/8'^^ 1/2'^^ 3/4' and 1' in Wooden Case^^National Pipe Taper Taps (NPT) are appropriate for threading a wide variety of materials both ferrous and non-ferrous^^The nominal size of a Pipe Tap is that of the pipe fitting to be tapped^^ not the actual size of the tap^^The thread tapers 3/4 of an inch per foot^^All Pipe Taps furnished with a 2-1/2 to 3-1/2 thread chamger^^NPT threads require the use of a 'sealer' like teflon tape or pipe compound.^^