Irwin Industrial Tools 4935058 SAE Alignment Dies 4 to 1/2-Inch with NC & NF Thread Pitches,IRWIN,4935058" /> These IRWIN dies start and thread straight virtually every time Each IRWIN die is made with more steel at critical points for additional strength High-carbon steel construction for added durability SAE measurements Sizes include: #4 to 1/2" and 1/8 - 27 NPT Contains 17 dies from No. 4 Machine to 1/2-Inch with National Corse and National Fine Thread pitches Dies features 1/8-Inch of additional steel in the form of a guide to align the die for threading, this also creates additional strength for the die High carbon Steel Construction Laser Etched Markings for easy identification