Spi 19-309-4 Class Zz Minus Plug Pin Gage 0.309 in

Product Description

The SPI 19-309-4 is a Class ZZ minus plug pin gage used to verify bore and hole dimensions in precision machining and inspection applications. It measures 0.309 inches in diameter and is manufactured from steel for durability and consistent dimensional stability. With a tolerance of 0.0002 inches, this gage is suited for go/no-go inspection workflows where tight dimensional control is required. Machinists, quality control technicians, and tool-and-die professionals use plug pin gages like this one as a reliable, low-cost method for confirming hole size compliance on the shop floor or in an inspection room.

This gage is appropriate for use in manufacturing environments where hole diameter verification is part of routine quality assurance. Class ZZ is the standard tolerance class for plug gages used in general inspection of production parts. The minus designation indicates the gage is ground to the low side of the nominal diameter, which is the standard configuration for go-gage applications. It is suited for use on ferrous and non-ferrous workpieces in both job shop and production settings.

Key Features

• 0.309 inches nominal diameter for precise bore inspection
• Class ZZ tolerance class — standard for general-purpose plug gaging
• Minus designation ground to low side of nominal for go-gage use
• 0.0002 inches tolerance for accurate dimensional verification
• Steel construction for wear resistance and dimensional stability

Compatibility

Designed as a general-purpose plug pin gage for use in standard go/no-go inspection setups compatible with 0.309 inches nominal bore diameter applications.

Installation Notes

Plug pin gages are handled and used by machinists and quality control technicians — no installation in the traditional sense is required. Keep the gage clean and lightly oiled when not in use to prevent corrosion. Do not force the gage into an undersized bore, as this can damage both the gage and the workpiece. Store separately from other gages and hard tooling to avoid surface damage that could affect accuracy.