Starrett 831C Small Hole Gauge, 0.300" - 0.400" Range, 3-3/8" Length

This small hole gauge is well balanced tool that is ideal for accurately measuring small holes, slots, grooves, and recesses in all kinds of work. Accurate measurement is obtained by slightly "rocking" this gauge in the hole to be measured. This will guarantee contact at the true diameter. The final size is then obtained by measuring over the ball contacts with a micrometer.

• Hardened-ball measuring surface with two-point contact, its gaging surface is a half-ball with a flat bottom which permits use in even the most shallow holes, slots, and recesses
• Radius of gauge is less than the minimum diameter to be measured, which provides the two-point contact necessary for maximum accuracy
• Smooth, sensitive adjustment for better feel, giving more accurate measurement
• The adjustment of the gauge beyond their range is restricted by a safety stop that prevents breakage