Spi 29-128-6 Class Zz Plus Plug Gage 0.128 in Diameter

Product Description

The SPI 29-128-6 is a Class ZZ Plus plug gage designed for precision bore and hole measurement in machine shop, quality control, and toolroom environments. Built from steel, this go/no-go style gage checks whether a drilled, reamed, or bored hole meets dimensional tolerance. The nominal diameter is 0.128 inches with a tolerance of 0.0002 inches, placing it in the tightest class of working-gage standards for general inspection work. Machinists, quality technicians, and toolroom professionals rely on this type of gage to verify hole size quickly and repeatably without the need for a measuring instrument readout.

Class ZZ Plus plug gages are used across a wide range of light industrial and precision manufacturing applications. Typical use cases include incoming inspection of machined components, in-process hole verification on production lines, and toolroom calibration tasks. At 0.128 inches nominal diameter, this gage is suited for small-bore work such as pin holes, pilot holes, and precision-drilled passages in metal components. It is appropriate for both job shop and production floor environments where consistent hole acceptance criteria must be enforced.

Key Features

• Class ZZ Plus tolerance rating at 0.0002 inches for tight-tolerance hole inspection
• 0.128 inch nominal diameter covers small-bore pin and pilot hole applications
• Steel construction provides durability and wear resistance under repeated use
• Compact single-piece gage format for fast, tool-free inspection checks
• Lightweight at 0.2 pounds for easy handling at the bench or on the floor

Compatibility

Designed as an OEM-style working gage for use wherever Class ZZ Plus plug gage standards apply to 0.128 inch nominal bore inspection in standard steel plug gage holders and handles.

Installation Notes

Plug gages require no tools for use but should be handled carefully to avoid surface damage that could affect accuracy. Store in a protective case away from other metal tooling when not in use. Calibration intervals should follow your facility quality plan or applicable metrology standards. Do not force the gage into an undersized hole, as this can damage the gage and invalidate measurement results.