12-28 UNJF (Left Hand) (mil-S-8879 Aerospace Military & Government) 3B Go & NoGo Thread Plug Assembly with Taperlock Style W/ Handle tool Steel Rc 60-62 cold stabilized work plug handles can be marked with 15 characters at no additional cost Inch handles will be light blue metric yellow Certificate of Accuracy is included NOTE: selection of a 2B or 3B is based on your requirements. A 2B class plug will have a larger pitch diameter for the NoGoThread member only. The Go member is the same regardless of the class chosen. A J is a special call out requiring special marking on plugs with a rounded Root Radius on thread rings. Long form certifications are strongly recommended for all UNJ style gages. Certificate of Accuracy is included.Click HERE to read about additional Long Form CERT. Click ADD below to add the gage to your cart. If you need the optional Long Form CERT Click on button below to add it to the cart. Use the back button to return to this page and click on Cart to check or modify your selections. You only require 1 long form cert for each gage purchased.