18.0MM-2.50MM 6g NoGo Ring Gage tool steel cold stabilized thread ring Rc 60-62 marked with size and tolerance Certificate of Accuracy is included. 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.