Spi 22-156-4 Class Zz Plug Gage Set 250 Piece

Product Description

The SPI 22-156-4 is a 250-piece Class ZZ plug gage set covering a diameter range of 0.251 to 0.500 inches. Each pin is manufactured from steel and held to a plus tolerance of 0.0002 inches, conforming to NIST traceable standards. The set is designed for shop-floor and inspection environments where fast, reliable hole measurement is required. Machinists, quality control technicians, and tool-room professionals use plug gage sets to verify bore diameters, measure slot widths, and confirm center-to-center distances between holes without the setup time required by variable measuring instruments.

This set is suited for production inspection in light manufacturing, precision machining, and metal fabrication environments. Class ZZ gages are the standard classification for working gages used in GO gage inspection applications. The 250-piece range from 0.251 to 0.500 inches provides comprehensive coverage for the most common small-bore and slot-width verification tasks found in both job-shop and high-volume manufacturing settings. The included pin gage holder keeps pins organized and accessible at the bench or inspection station.

Key Features

• 250-piece set spanning 0.251 to 0.500 inches in diameter
• Class ZZ tolerance classification with a plus tolerance of 0.0002 inches
• NIST traceable Certificate of Accuracy included with the set
• Steel construction for durability in production and inspection use
• Pin gage holder included for organized storage and bench access
• Suitable for GO gage inspection, hole sizing, slot width measurement, and hole-spacing calculations

Compatibility

Designed as a standard Class ZZ plug gage set for use in any inspection or machining environment requiring hole and slot measurement in the 0.251 to 0.500 inch diameter range.

Installation Notes

Plug gages are hand tools and do not require installation; however, proper handling is essential to maintain accuracy. Keep pins clean and lightly oiled to prevent corrosion and wear. Never force a pin gage into a bore — if the pin does not enter under light hand pressure, select the appropriate size. Store pins in the provided holder when not in use to prevent damage to the ground surfaces.