Spi 29-921-4 Class Zz Plus Plug Gage 0.921 in Dia

Product Description

The SPI 29-921-4 is a Class ZZ Plus plug gage designed for precision bore and hole inspection in machining and manufacturing environments. Measuring a nominal diameter of 0.921 inches with a tolerance of 0.0002 inches, this go/no-go style gage provides reliable pass-fail verification on the shop floor or in a quality control setting. Constructed from steel for durability and dimensional stability, it is used by machinists, tool-and-die makers, and QC inspectors who require consistent, repeatable measurement results on drilled, reamed, or bored features.

Class ZZ Plus plug gages are appropriate for general-purpose inspection of production parts where hole diameter conformance must be verified quickly and accurately. This gage is suited for use in light manufacturing, job shops, and production facilities working to standard inch tolerances. It is particularly useful when inspecting holes sized to 0.921 inches across a range of materials and part types.

Key Features

• Nominal measurement diameter of 0.921 inches for precise hole inspection
• Class ZZ Plus tolerance of 0.0002 inches for general-purpose production gauging
• Steel construction for wear resistance and long service life
• Compact and lightweight at 0.2 pounds for easy handling during inspection
• Single-piece package quantity for individual replacement or supplemental use

Compatibility

Designed as a general-purpose Class ZZ Plus plug gage for inspection of 0.921-inch nominal diameter holes in standard production and quality control applications.

Installation Notes

Plug gages are handled and used by machinists or quality control technicians — no power source or shutoff is required. Keep the gage clean and lightly oiled when not in use to prevent corrosion on the steel surfaces. Do not force the gage into an undersized hole, as this can damage both the gage and the workpiece. Store in a protective case away from abrasive materials to maintain calibration integrity.