Starrett BG802 6 Screw Pitch Gauge tpi 4-42

Screw pitch gauges quickly determine the pitch of various external and internal threads. These gauges consist of a substantial steel case with a number of folding leaves at both ends, each leaf having teeth corresponding to a definite pitch.
American national - 60° threads
No. of leaves: 30
TPI range: 4 - 42
Locking device.