3 pairs of FMS thread inserts (types 21A, 21B & 21C) can measure the external pitch diameter of threads
with a flank angle from 55º to 80º and pitches from 1mm – 8mm / 24 TPI – 3 TPI.
The same applies to types 22 and 23 A, B & C for internal thread pitch diameter.
Threads with a flank angle of 29º and 30º are made for specific pitches
because of the steep flank angle.
