Use these bore gauges to measure the inside diameter of holes and cylindrical bores, as well as identify out-of-roundness problems. Since they measure in increments of 0.0005", they’re useful for general checks. They’re often used to test parts where deviations in roundness or size can lead to wear or inefficiency, such as in engine cylinders, machine components, and turbines. Unlike calipers and inside micrometers, these bore gauges have a long shaft to reach into deep cylinders. They have a two-point contact system, which is the most common design for bore gauges.

To use these bore gauges, set a baseline measurement with a ring gauge, calibrator, micrometer, or caliper. The variation from the set measurement displays on the dial right away, so there’s no need for conversions. Swap out the anvil to measure bores of different diameters. All these gauges have jeweled bearings that resist wear for a long service life.

For technical drawings and 3-D models, click on a part number.

No need for other tools to set a baseline diameter—these bore gauges have a built-in micrometer head. Use them to check diameters and test for issues with roundness in engine cylinders and other parts. They have a two-point contact system, which is the most common design for bore gauges. For a long service life, the jeweled bearings in the dial head resist wear, and a plastic cover protects the head from scratches and drops. With hollow grips, these bore gauges are easy to hold and prevent heat from your hands from skewing accuracy.

To use them, set a baseline measurement with the micrometer head. As you move the gauge in the hole, the variation from the set measurement displays on the dial right away. Switch out the anvil to measure bores of different diameters.

Check a hole’s diameter and detect out-of-roundness problems. Often used to test engine cylinders and machine components, these gauges catch issues with roundness and taper. They have the most common design for bore gauges, which is a two-point contact system. The dial head’s highly sensitive jeweled bearings resist wear for a long service life.

To use these bore gauges, set a baseline measurement with a ring gauge, calibrator, micrometer, or caliper. The variation from the set measurement displays on the dial right away, so there’s no need for conversions. Swap out the anvil to measure bores of different diameters. Marked by size, the anvils are quick to spot and select.

Test for size deviations across a range of hole diameters. These sets include 3 gauges and over 25 anvils marked by size for quick changes. Use them to test engine cylinders, machine components, and other parts for issues with roundness and taper. They have a two-point contact system, which is the most common design for bore gauges. For a long service life, the jeweled bearings in each dial head resist wear, and a plastic cover protects the head from scratches and drops.

Check size deviations by first setting the desired measurement with a ring gauge, bore gauge calibrator, micrometer, or caliper. The dial will display the magnitude of variation from the set measurement.

Check roundness, taper, and diameter near the bottom of bores—the flat bottom on these gauges positions the anvil against the base of the hole. Because they reach down into bores, they are a better choice for measuring deep holes than calipers or inside hole micrometers. They are comparison gauges—the dial will display the magnitude of variation from the set measurement. Set your desired measurement with a ring gauge, bore gauge calibrator, micrometer, or caliper.

The anvil on the gauges extends out and contacts two points to take measurements. Swap the included anvils to measure bores with different diameters. An internal pendulum keeps these gauges centered as they slide into a bore and positions the anvils perpendicular to the bore surface. This results in more contact with the bore for consistent and accurate measurements. These gauges have hollow grips for easy handling. They also prevent body heat from causing the material of the gauge to expand and impact accuracy. A plastic cover on the dial protects it from drops and scratches.

With a short stem, these gauges easily maneuver in shallow holes and are compact enough to slip into your pocket. Use them to check the diameter and roundness of a hole. They are comparison gauges—the dial will display the magnitude of variation from the set measurement. Set your desired measurement with a ring gauge, bore gauge calibrator, micrometer, or caliper.

The anvil on the gauges extends out and contacts two points to take measurements. Swap the included anvils to measure bores with different diameters. These gauges have hollow grips for easy handling. They also prevent body heat from causing the material of the gauge to expand and impact accuracy. A plastic cover on the dial protects it from drops and scratches.

Find a hole’s ID without having to compare it against a set measurement like you do with dial bore gauges. These gauges have an LCD display, making it easy to read the diameter. To measure holes with different diameters, swap out the anvil. Each anvil has two contact points to detect out-of-roundness. Use them to find issues with size that can cause precision parts, such as engine or valve cylinders, to wear quickly or run poorly. All have zero-position memory, also known as absolute (ABS) positioning, which retains the gauge’s measuring position when turned off. A zero-set button allows you to start measuring at any point.

Extensions (sold separately) lengthen the stem of your gauge to reach farther into deep bores.