3M 26104, PPS Series 2.0 Adapter, Type S20, 1/8 Male, 27 Thread NPSM, 7100135929 
Insize 4801-16E, RADIUS GAGE, 17/64″-1/2″, 6928640330063
$26.64
Radius Gage Set Range 17/64″ to 1/2″
16 Internal Leaves and 16 External Leaves
Accuracy +/- .0014
Made of medium carbon steel
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