1" UNF

  1" UNF Tap
 
  12 tpi Standard UNF pitch
  60mm Long Series Flute / Cutting Length for full thread, deep holes.
  125mm Overall, 20mm Shank and 15mm Square Drive.
  4 Flutes, Centred Both Ends.
 
  Manufactured in UK by FBT, Firth Brown Tools Ltd, a now defunct premium English brand.