This product is a 3/8-16 NC-2 thread plug gage from the brand Perfex. It is used for metalworking inspection and measurement, specifically for checking the accuracy of a thread. The gage includes a GO gauge with P.D. of .3344 and a NOGO gauge with P.D. of .3299, allowing for precise measurements and inspections in industrial settings. Its compact size and specific design make it a valuable tool for ensuring quality control in threaded components.