Spi 29-375-3 Class Zz Plus Plug Gage 0.375 Inch

Product Description

The SPI 29-375-3 is a Class ZZ Plus plug gage designed to verify inside diameter dimensions to a nominal size of 0.375 inches. Built from steel, this go/no-go style instrument delivers a tolerance of 0.0002 inches, making it suitable for inspection and quality control work where dimensional accuracy is critical. Machinists, toolroom technicians, and quality assurance personnel use plug gages to confirm that bored, drilled, or reamed holes meet print specifications. The Class ZZ Plus designation indicates a standard commercial tolerance grade appropriate for general-purpose inspection of production parts.

This plug gage is used in machine shops, manufacturing facilities, and toolrooms to inspect hole diameters in metal, plastic, and composite workpieces. It is well suited for incoming inspection, in-process checks, and final part verification on production runs. The 0.375 inch nominal diameter makes it a commonly needed size for fastener clearance holes and precision bores found across general metalworking and fabrication applications.

Key Features

• Nominal measurement diameter of 0.375 inches for precise bore inspection
• Tolerance of 0.0002 inches for accurate Class ZZ Plus classification
• Steel construction for durability and wear resistance in shop environments
• Compact and lightweight at 0.2 pounds for easy hand use during inspection
• Class ZZ Plus grade suitable for general-purpose production inspection work

Compatibility

Designed as a standard Class ZZ Plus plug gage for general inspection of 0.375 inch nominal inside diameters in production and toolroom environments.

Installation Notes

Plug gages are handled and used by machinists or quality technicians and do not require installation in the traditional sense. Store the gage in a clean, dry location and allow it to reach ambient temperature before use to avoid thermal expansion errors. Handle with clean hands or cotton gloves to prevent corrosion from skin oils. Do not force the gage into a bore; excessive insertion force indicates the hole is undersized and can damage the gage surface.