note points of thread plug gage/gauge. Ring gage/gauge.

screw thread gauge/gages have two kinds, they offen are used to checking the size about screw thread.

The size about thread gauge/gage is made of diameter and distance of thread.

The way about test measuring: first, when you use the thread gauge/gage to check the thread to be tested, you have to clean up the oil and dirt about thread. Then let ring gauge/gage and thread which need tested face to face. Next with the thumb and index finger rotating ring, if it is screwed in the free state is determined by the length of the thread of all , the thread is good and ok. On the contrary. It’s bad .

So the thread gages /gauges a tool about checking the thread of items which are producted by factory.