Milliard 6-Inch Duct Flange Multi-purpose. Use it with any 6in. air duct system. Great for home & garden use. Professional and durable. Designed for use with Milliard Aluminum Foil Duct, the Milliard Inline Carbon Filter or Milliard 6in. Ducting Clamps. Installs quickly over pre-existing holes or ports and can be fitted to a variety of applications or materials. Couple two flanges back-to-back for a secure, removable fitting that connects ducts together. Includes flange, collar fitting, and installation screws.