Van Keuren Standard Thread Ring Gages Set GO/NOGO Van Keuren's Thread Gages allow you to inspect the pitch diameter for threaded products.All stock Thread Ring Gages are made to Class X tolerances per ASME B1.2 (Unified Inch Screw Threads).A Certificate of Accuracy is included with each gage.Available in 2A or 3A, and each Thread Ring Gage is marked with nominal size, threads per inch, class of fit and pitch diameters.Features include... 5/8-18 UNF Threads GO and NO GO Set Certificate of Accuracy included Made from Tool Steel, 60/62 Rc. Select 2A or 3A from Pull Down Menu. Ring Gage 2A... GO Gage Length: 9/16" NO GO Gage Length: 9/16" GO Pitch Diameter: 0.5875" NO GO Pitch Diameter: 0.5828" Ring Gage 3A... GO Gage Length: 9/16" NO GO Gage Length: 9/16" GO Pitch Diameter: 0.5889" NO GO Pitch Diameter: 0.5854"