The dial on these gauges displays size deviations in real time. These gauges measure small slots and bores in precision parts, such as electronics, where even small size deviations can cause inefficiencies. Thanks to its full-ball design, the end of these gauges makes 360° contact inside the bore, so it's easier to center in tight spaces than anvil or spring-loaded contacts. This symmetrical ball is also less likely to tilt within the bore than half-ball gauges, which helps to avoid skewed measurements from improper placement.

Insert the probe into a bore and turn the knob on the handle to expand the contacts. To check size deviations, set 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. To find the bore diameter, use a micrometer to measure the distance across the contacts.

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

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.

Measure the inside diameter of holes and cylindrical bores, as well as identify out-of-roundness problems. These gauges are often used to test engine cylinders, machine components, and other parts for issues with roundness and taper. They have the most common design for bore gauges—a two-point contact system. Even if the gauge is tilted, an internal pendulum balances the contact points at the true center of a hole. Hollow grips make these gauges easy to hold and prevent heat from your hands from skewing accuracy. For a long service life, the dial head has highly sensitive jeweled bearings that resist wear. Its plastic cover protects against scratches and drops.

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.

Detect variations in a range of hole diameters and depths. These sets include one dial head that fits onto three gauge bodies and 26 anvils to switch out for different holes. 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. An internal pendulum balances the contact points at the true center of a hole, even if the gauge is tilted. To prevent heat from your hands skewing accuracy, all the gauges have hollow grips, which also make them easy to hold. The dial head’s highly sensitive, wear-resistant jeweled bearings contribute to a long service life, and its cover protects against 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 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.

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.

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.

Check the top diameter of chamfered holes to make sure they’re within tolerance. These gauges are often used for quality control in milling, drilling, and reaming. Press the three-blade probe into a chamfered hole and twist slightly to center. Once the blades touch the hole’s slopes, the dial will display the diameter. Zero-set these gauges on a flat, ground surface when needed.

Choose a gauge with a measuring angle that’s greater than or equal to the angle of the chamfered hole you’re measuring.

Whether a chamfered edge is in a screw hole or on the end of a rotary shaft, these gauges find its diameter. Use them to confirm the tolerance of edges after milling, drilling, and reaming. They measure chamfers on the inside or outside diameter of your bore. As you trace the probe of these gauges along an edge, an internal sensor records the distance and angle. The calculated diameter displays on the LCD screen for quick readings. All have SPC data output to transfer information to your computer or data processor—you don’t even need any cables.

Choose a gauge with an angle that is greater than or equal to the chamfer angle you are trying to measure.

Make sure the top diameter of a chamfered hole isn’t too big or too small. These gauges are often used as a quality control check after milling, drilling, and reaming. Press the three-blade probe into a chamfered hole and twist slightly to center. Once the blades touch the hole’s slopes, the dial will display the diameter. Zero set these gauges on a flat, ground surface when needed.

Choose a gauge with a measuring angle that’s greater than or equal to the angle of the chamfered hole you’re measuring.

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

Short, narrow contacts allow these calipers to take hard-to-reach measurements, such as the dimensions of internal grooves and slots.

Choose calipers with a handle for a more comfortable one-handed grip.

These calipers come with a calibration certificate traceable to NIST that states they've passed a test for accuracy. Short, narrow contacts allow them to take hard-to-reach measurements, such as the dimensions of internal grooves and slots. All are IP67 rated for protection from dust and temporary water submersion. They have a zero-set button which allows you to start measuring at any point.

Short, narrow contacts allow these calipers to take hard-to-reach measurements, such as the dimensions of internal grooves and slots. They are IP67 rated for protection from dust and temporary water submersion. Each has a zero-set button which allows you to start measuring at any point.

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.