Vermont NPT Tapered Pipe Thread Plug Gage Assemblies These Thread Plug Gages allow you to check tapered and straight internal pipe threads. Perfect for inspecting standard pipe and pipe fittings.These Vermont Pipe Thread Plug Gages are made to precise Class X tolerances per ASME B1.20.1 and include a Certificate of Accuracy. Each Thread Plug Gage includes Handle - light blue in color.Select Specific Thread Size from Pull Down Menu.