from this... to this!
From this....  TO THIS!

All fittings meet or exceed the recommendations of ANSI/API 14.3, A.G.A. #3, A.S.M.E, and numerous other professional organizations.

This fitting reigns as the most widely used means of measurement for natural gas. It saves users time and money by providing a fast and simple method of changing orifice plates under pressure without flow interruption, preventing unscheduled shutdowns. In addition, the dual-chamber design eliminates the burden of bypass piping, valves and other fittings required with conventional orifice flange installations.