Spi 29-387-8 Class Zz Plus Plug Gage 0.387 in Dia

Product Description

The SPI 29-387-8 is a Class ZZ Plus plug gage designed for go/no-go dimensional inspection of bored holes, drilled passages, and machined apertures. The gage measures a nominal diameter of 0.387 inches with a tolerance of 0.0002 inches, providing the close-tolerance verification required for precision machining and quality control workflows. Machined from steel, this plug gage is used by machinists, toolmakers, inspection technicians, and trade professionals who need reliable, repeatable hole-diameter confirmation on the shop floor or at incoming inspection stations.

This plug gage is suited for use in manufacturing, machine shops, HVAC component fabrication, and general metalworking environments where hole diameter conformance must be verified against tight dimensional specifications. It is appropriate for both production-line spot checks and detailed quality assurance inspections. The compact, single-piece format makes it easy to handle and store in standard gage blocks or inspection kits.

Key Features

• Nominal measurement diameter of 0.387 inches for direct hole-size verification
• Class ZZ Plus tolerance rating of 0.0002 inches for precision dimensional inspection
• Steel construction for durability and dimensional stability under repeated use
• Compact, single-piece design compatible with standard gage storage and handling practices
• Weighs 0.2 pounds, lightweight enough for bench or portable inspection use

Compatibility

Designed as an OEM-style replacement or direct-use plug gage for any application requiring Class ZZ Plus go/no-go hole inspection at a nominal diameter of 0.387 inches.

Installation Notes

Plug gages are used by inspection technicians and machinists and do not require mechanical installation. Before use, ensure the gage and workpiece are at the same ambient temperature to avoid thermal expansion errors. Handle the gage by its body, not the measuring pin, and avoid dropping or striking it against hard surfaces, as impact can alter its calibrated dimensions. Store in a protective case or gage block when not in use to maintain accuracy.