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-63 to CF Conflat 3 3/8 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.