Spi 29-400-9 Class Zz Plus Plug Gage 0.4 Inch

Product Description

The SPI 29-400-9 is a Class ZZ Plus plug gage designed to verify the dimensional accuracy of machined holes and bores. It provides a go/no-go reference standard for inside diameter inspection, confirming that a hole falls within the specified tolerance range. The gage measures at a nominal diameter of 0.4 inches with a tolerance of 0.0002 inches, making it suitable for precision quality-control work in machining, fabrication, and assembly environments. The steel construction provides durability under repeated use in shop-floor conditions. Machinists, quality technicians, and tool-and-die professionals use plug gages of this class as part of standard inspection protocol.

Class ZZ Plus plug gages are used in production and inspection settings where hole diameter verification is required before parts advance to assembly or final inspection. This gage is appropriate for use on drilled, reamed, or bored holes in metal workpieces where dimensional conformance is critical. It is suited to both job-shop environments and higher-volume production lines where consistent go/no-go inspection methods are standard practice.

Key Features

• Nominal measurement diameter of 0.4 inches for consistent bore inspection
• Tolerance of 0.0002 inches provides precise Class ZZ Plus accuracy
• Steel construction for wear resistance and long service life in shop environments
• Compact and lightweight at 0.2 pounds for easy single-hand operation
• Single-piece package quantity suited to individual workstation or toolbox use

Compatibility

Designed as an OEM-style replacement or direct-use plug gage for inspection of machined holes at 0.4 inch nominal diameter in standard Class ZZ Plus gage applications.

Installation Notes

Plug gages should be handled with clean, dry hands or lint-free gloves to prevent corrosion from skin contact. Before use, verify the gage and workpiece are at the same ambient temperature to avoid thermal expansion error. Do not force the gage into an undersized hole, as this can damage the gage or the workpiece surface. Store the gage in its protective case when not in use to maintain calibration integrity.