These double claw clamps, made of Aluminum, fit ISO-K DN 320 thru 500 vacuum flanges and follow vacuum technology standards described in DIN 28404 and ISO 1609. The ISO-K style fittings are quick to assemble using claw clamps (please see figure - click to enlarge) and can be connected in any orientation. The claw clamp hooks into a ridged groove in the back side of the ISO-K vacuum flange. The union requires a centering ring which contains rubber, elastomeric, O-ring to form the vacuum seal between the two flange faces. The clamps are commonly used to build process vacuum plumbing and systems for industrial vacuum applications. The ISO standard sizes for large LF flanges are ISO-LF DN 63, 80, 100, 160, 200, 250, 320, 400, 500, 630, 800, and 1000. These double claw clamps are made of aluminum and work with flange sizes ISO-LF 320, 400, and 500. The quantity of clamps required per flange size is given below.