Trilock Plug Gage AssembliesTrilock Plug Gage Assemblies When you need to inspect large diameters, Trilock Plug Gage Assemblies are your best solution. These assemblies include a GO member on one end and a NOGO member on the other end, both connected to the handle in the middle. When one end wears out, much like a Reversible Plug Gage, simply turn the member around and continue gaging, significantly increasing the life of the gage. Members are securely attached to your Trilock