0.55UNM Plug Go Gage pitch .125mm; UNM stands for “United National Miniature” the American Metric miniature Thread standard. Precision Thread Gage made of High Speed Steel then hardened. Picture is representative of part. Brand is; MiniTaps made to our specification in Switzerland. The purchase of this item Includes: the thread Gage, Handle with serial number engraved, and Certificate tied to the serial number with factory measurements and the thread standards.