Spi 23-129-0 Threaded Ring Gage 4-48 Class 2A Go No Go

Product Description

The SPI 23-129-0 is a double-ring threaded ring gage used to verify the external thread dimensions of fasteners and threaded components machined to a No. 4-48 UNF thread specification. Built from tool steel and manufactured to Class 2A tolerance standards, this gage provides both Go and No Go members in a single double-ring configuration, allowing machinists and quality technicians to confirm that a threaded part falls within acceptable dimensional limits. NIST traceability certification is included, supporting documented quality control and inspection recordkeeping requirements in production or tool-room environments.

This gage is suited for inspection of No. 4-48 UNF externally threaded parts in precision manufacturing, aerospace component fabrication, and general machining shops. It is used on the shop floor and in quality labs wherever small-diameter unified fine threads must be verified against Class 2A fit requirements. The double-ring design consolidates Go and No Go inspection into a single, compact tool, reducing handling time during incoming or in-process inspection.

Key Features

• Go and No Go members combined in one double-ring gage for efficient pass/fail inspection
• Thread size No. 4-48 UNF, Class 2A tolerance classification
• Tool steel construction for wear resistance and dimensional stability
• NIST traceability certification included for documented inspection programs
• Compact form factor suited to bench inspection and floor use

Compatibility

Designed for inspection of externally threaded components with a No. 4-48 UNF thread form manufactured to Class 2A tolerance limits.

Installation Notes

Threaded ring gages are used by machinists, quality technicians, and inspection personnel — no installation in a mechanical system is required. Handle the gage with clean, dry hands or cotton gloves to prevent corrosion on the tool steel surfaces. Store the gage in its case when not in use and periodically verify it against a setting plug to confirm it has not worn out of tolerance. Do not force the gage onto a thread; resistance indicates the part does not meet the Go limit and further machining or rejection is required.