The Starrett® 456 gear tooth vernier caliper is designed to measure in 0.001 in or 0.02 mm the thickness of gear teeth at the pitch line (the chordal thickness of the teeth) using the distance from the top of a tooth to the chord. For the same purpose, it can also be used for measuring hobs, form and thread tools.

Starrett® Gear Tooth Vernier Caliper, Series: 456, 0 to 1-1/4 in Measuring, +/-0.0005 in/ft Accuracy, Graduations: 0.001 in, Measuring System: Imperial, Adjustable Screw Nut, 4-1/4 in H Dimensions

• Adjusted independently by screws on the graduated bars
• Thickness of a tooth at the pitch line is measured by an adjustable jaw after the addendum is set by the adjustable tongue
• Caliper is designed to measure in 0.001 in or 0.02 mm the thickness of gear teeth at the pitch line using the distance from the top of a tooth to the chord
• 20 - 2 diametral pitch