Spi 19-391-2 Class Zz Minus Plug Pin Gage 0.391 in

Product Description

The SPI 19-391-2 is a Class ZZ minus plug pin gage machined from steel, used to verify that a hole or bore falls within a specified minimum acceptable size. With a nominal diameter of 0.391 inches and a tolerance of 0.0002 inches, this gage provides reliable go/no-go measurement for quality control and inspection work. Class ZZ is the standard tolerance class for general-purpose inspection gages used in production and shop-floor environments. Machinists, toolmakers, and quality control technicians rely on pin gages like this one to confirm dimensional conformance without the variability of calipers or micrometers.

This plug pin gage is suited for use in machine shops, fabrication facilities, and manufacturing inspection stations. It is applied wherever a 0.391-inch diameter hole must be verified for minimum acceptable size — including checking drilled, reamed, or punched holes in metal, plastic, or composite workpieces. The minus designation means the gage is manufactured to the lower end of the nominal size, confirming that a hole is not undersized.

Key Features

• Class ZZ tolerance class for general-purpose shop and production inspection
• Minus designation confirms minimum acceptable hole size
• 0.0002 inches tolerance for precise dimensional verification
• Steel construction for durability under repeated use
• 0.391 inches nominal diameter for direct hole conformance checking

Compatibility

Designed as a general-purpose plug pin gage for use in standard go/no-go inspection applications requiring a 0.391-inch nominal diameter Class ZZ minus gage.

Installation Notes

Pin gages are handled and used by machinists and quality control inspectors following standard metrology practices. Store the gage in its protective case when not in use to prevent damage to the precision-ground surface. Clean the gage and the bore being measured before use to avoid false readings caused by chips or contamination. Do not force the gage into a bore — controlled, light hand pressure is the correct technique.