Temotuf TFME3004045A 9/16" - 18 Unf Double Ended Screw Plug Gauge - Go & No Go
Made of bearing steel GCr15, HRC58-62
Typically used to check the internal threads of products
The Go thread plug gauge must enter and pass through the full-threaded length of the product freely and the No Go thread plug gauge should never fit into the product for more than 3 turns