The product is a set of thread ring gages made by Mercury, specifically designed for inner diameter of 5/16 inches and thread class UNF 3A. The gages include a Go pitch diameter of .2854 inches and a No Go pitch diameter of .2827 inches.  Made in the United States, these gages are essential tools for ensuring high-quality and accurate craftsmanship in various industrial applications.PLEASE MAKE SURE YOU HAVE A LOOK 👀 AT ALL MY OTHER LISTINGS ON EBAY !