These 90 degree elbow vacuum fittings follow International Standards Organization (ISO) standards and have (2) ISO-63 and (1) KF-16 Port. ISO flanged vacuum fittings are commonly used to build process vacuum plumbing and systems for industrial applications. They are manufactured at Ideal Vacuum Products. The fittings are quick to assemble using double claw clamps and a Viton or Buna rubber elastomer centering ring. The ISO standard sizes for ISO NW 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 fittings are made of corrosive resistant stainless steel.