Keep dozens of plug gauges on hand to check a range of hole sizes. You’ll often hear them called pin gauges. Use them to measure hole size and depth with precise go/no-go tests, check hole location and distance, and set micrometers. Sets include a manufacturer's certificate of accuracy to certify diameters are within tolerance. Gauges are tool steel, so they’re strong, hard, and resist wear.

If a go gauge can enter the hole and a no-go gauge is unable to enter, the hole is within tolerance. Go gauges check the minimum hole diameter. No-go gauges check the maximum hole diameter.

Choose a class based on the level of precision you need—the smaller the tolerance, the greater the accuracy. Classes are based on ASME standard B89.1.5, which states diameter won’t vary more than the listed plug gauge tolerance. Class X gauges are the most accurate type we sell. Use them for high-precision work. Class Z gauges are the most common. You'll often find them used on shop floors. Class ZZ gauges are ideal for quick checks that don't require extreme precision.

Black-oxide tool steel gauges show wear patterns, so you know when to calibrate or replace them.