Vermont Standard Thread Plug Gage Assembly, GO/NOGO, Vermont's Thread Gages allow you to inspect the pitch diameter and the functional thread for internal threaded products.All stock Thread Plug Gages are made to Class X tolerances per ASME B1.2 (Unified Inch Screw Threads), ASME B18.29.1 (STI Inch Screw Threads), and ASME B1.16M (Metric M Series Screw Threads).A Certificate of Accuracy is included with each gage.Available in 2B or 3B, and each Thread Plug Gage is marked with nominal size, threads per inch, class of fit and pitch diameters.Features include... 5/16-28 UN Threads GO and NO GO Set Certificate of Accuracy included Select Taperlock, Reversible or Set Plug from Pull Down Menu. Taperlock Plug 2B... GO Gage Length: 1/2" NO GO Gage Length: 5/16" GO Pitch Diameter: 0.2893" NO GO Pitch Diameter: 0.2937" Taperlock Plug 3B... GO Gage Length: 1/2" NO GO Gage Length: 5/16" GO Pitch Diameter: 0.2893" NO GO Pitch Diameter: 0.2926" Set Plug 2A... GO Gage Length: 3/4" NO GO Gage Length: 3/4" GO Pitch Diameter: 0.2883" NO GO Pitch Diameter: 0.2849" Set Plug 3A... GO Gage Length: 3/4" NO GO Gage Length: 3/4" GO Pitch Diameter: 0.2893" NO GO Pitch Diameter: 0.2867" Select Taperlock or Set Plug from Pull Down Menu.