3M 45093, Roloc Disc Pad TR, Extra Hard 3 in 1/4-20 Internal, 7000045285 
Insize 4131-1A2, AMERICAN STANDARD THREAD PLUG GAGE, 1/2-20UNF, 6928640359026
$101.38
Class 2B.
Standard ANSI/ASME B1.2
Supplied with Go and No-Go gages together
Supplied with manufacturer inspection certificate.
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