Ring Gauges | McMaster-Carr

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System of Measurement

Gauge Size

Gauge Measurement Type

Master

No-Go

Size-Checking Gauge Class

Thread Size

Thread Type

Surface Smoothness, RMS

4 μin

8 μin

Thread Fit

Metric Class 6g

Unified Standard Class 2A

Unified Standard Class 3A

Export Control Classification Number (ECCN)

EAR99

DFARS Specialty Metals

REACH

RoHS

Material

Hardness

Pipe Size

Certificate Type

Accuracy Certificate Traceable to NIST

Calibration Certificate Traceable to NIST

Pitch

Thread Direction

For Ring Gauge Size

9.271 mm to 12.954 mm

12.954 mm to 20.955 mm

20.955 mm to 28.829 mm

28.829 mm to 38.354 mm

Overall Length

Screw Size

871 Products

Size Checking

Ring Gauges for Outside Diameters

Use these gauges to check the outside diameter of shafts, rods, and other cylindrical objects to determine whether they’re in tolerance.

Master Ring Gauges

Set inside micrometers, dial bore gauges, and other precision tools.

Ring Gauge Holders

Often used with go and no-go ring gauges, these holders keep two ring gauges still for quick, repeat measuring.

Threaded Ring Gauges with Calibration Certificate

Not only were these gauges calibrated in a lab, but they also come with a certificate that's traceable to NIST.

Threaded Ring Gauges

Check a part’s external threads to make sure they fall within tolerance. You can use these for bolts, threaded rods, bits, and more.

Threaded Ring Gauges for Pipe
Threads with Calibration Certificate

These gauges come with a certificate that’s traceable to NIST, confirming they were calibrated in a lab. Use them to verify whether external pipe threads are within tolerance.

Threaded Ring Gauges for Pipe Threads

Confirm that external pipe threads are sized within tolerance.

Threaded Ring Gauge Holders

Join two ring gauges with different sizes to quickly check if threads are within tolerance. Secure your gauges to these holders with the included fasteners.

Left-Hand Threaded Ring Gauges

Test if the left-hand threads on parts fall within tolerance.

Left-Hand Threaded Ring Gauges
with Calibration Certificate

Calibrated in a lab and backed by a certificate traceable to NIST, these gauges check if left-hand threads fall within tolerance.