These ISO LF NW to Conical Conflat adapter vacuum fittings follow International Standards Organization (ISO) and Conflat standards. They have a flange sizes of ISO LF NW-80 to CF Conflat 3.38 inch. ISO flanged vacuum fittings are commonly used to build process vacuum plumbing and systems for industrial applications. The fittings are quick to assemble using double claw clamps and a centering ring (please see top right figure - click to enlarge). The Viton® centering ring contains a rubber/elastomeric o-ring. The ISO standard sizes for large flanges are NW-63, NW-80, NW-100, NW-160, NW-200, NW-250, NW-320, NW-400, NW-500, NW-630. These vacuum flages are made of corrosive resistant stainless steel. Conflat® is a registered trademark of Varian Corporation.