Spi 29-370-4 Class Zz Plus Plug Gage 0.37 Inch

Product Description

The SPI 29-370-4 is a Class ZZ Plus plug gage designed to verify bore and hole diameters to a precision tolerance of 0.0002 inches. Machined from steel, this go/no-go style gage is used in dimensional inspection to confirm that a drilled, reamed, or bored feature meets a specified diameter of 0.37 inches. Class ZZ Plus gages meet standard tolerance grades for general-purpose inspection work. Machinists, quality control technicians, and tool-and-die professionals rely on plug gages like this one to quickly confirm part conformance without the need for measurement instruments requiring manual reading.

This plug gage is suited for shop-floor and inspection-room use in environments where repeatable hole-size verification is required. Typical applications include checking drilled or reamed holes in metalworking, manufacturing, and fabrication operations. The 0.37-inch nominal diameter makes it appropriate for standard fractional and close-decimal bore inspection. It is a single-end gage used in production inspection, incoming quality control, and first-article verification across light industrial and precision machining environments.

Key Features

• Class ZZ Plus tolerance grade for general-purpose hole inspection
• 0.0002 inch tolerance for precise dimensional verification
• 0.37 inch nominal diameter measurement
• Steel construction for durability and dimensional stability
• Compact and lightweight at 0.2 pounds for easy handling

Compatibility

Designed as an OEM-style plug gage for general-purpose inspection of 0.37 inch diameter bores in standard machining and manufacturing applications.

Installation Notes

Plug gages are handled and used by machinists and quality control technicians and do not require installation in the traditional sense. Store and handle the gage carefully to prevent damage to the precision-ground surfaces, as nicks or burrs will compromise measurement accuracy. Clean the gage and the bore being checked before use to remove chips, oils, or debris that could cause false readings. Periodic calibration against certified masters is recommended to maintain traceability to measurement standards.