- Set of 2 Rougher and finisher 1 3/8 UNF
- Use to produce threads for helical coil wire screw thread inserts only
- S.T.I. taps are oversized so the thread produced accepts a helical coil wire screw thread insert of the same nominal
- size and pitch
- Taps are marked with the nominal size and pitch of the bolt to be used
- Taps are marked with “S.T.I."
- Part Number ES-12519