Spi 23-157-1 Threaded Ring Gage 5/16-18 Class 2A Go No Go

Product Description

The SPI 23-157-1 is a double-ring threaded ring gage used to verify the external thread dimensions of fasteners and threaded components to a 5/16-18 thread size at a Class 2A tolerance. The set includes both a Go ring and a No Go ring in a single tool, allowing machinists and quality control technicians to confirm that threads fall within the acceptable tolerance band without requiring separate gages. Constructed from tool steel for durability and dimensional stability, this gage is traceable to NIST standards and includes a traceability certification. It is a standard instrument in thread inspection workflows on the shop floor or in a QC lab.

This gage is used wherever precision thread verification is required on 5/16-18 externally threaded parts, including bolts, studs, and machined components. It is suited for production environments, incoming inspection stations, and job shops that must verify thread conformance to Unified National thread standards. The Class 2A classification covers the most common general-purpose external thread tolerance class used in commercial and industrial fastener applications.

Key Features

• Double-ring design includes both Go and No Go gages in one unit
• Thread size: 5/16-18 Unified National Coarse (UNC)
• Class 2A tolerance classification for general-purpose external threads
• Tool steel construction for wear resistance and long service life
• NIST-traceable with traceability certification included
• Compact form factor suited for bench or field inspection use

Compatibility

Designed for inspection of externally threaded 5/16-18 fasteners and components manufactured to Class 2A tolerance per Unified National thread standards.

Installation Notes

Threaded ring gages are used by machinists and quality technicians and require no installation. Handle with clean, dry hands or lint-free gloves to prevent corrosion on the precision-ground surfaces. Store in a protective case away from abrasive materials when not in use. Periodic calibration against a certified setting plug is recommended to maintain measurement accuracy.