Check the listing for details. Promaster Interior Framing Support System for units with 14" x 14" opening. Condition: New without tags. Listed at 79.00 USD. Patent Pending. Interior Framing Support System. Adds support when installing a Maxxair Fan or an AC unit requiring a 14" x 14" opening with one of our Patent Pending Roof or AC Adapters for the Promaster. They are made of Expanded PVC material. Much easier to work with than wood. They also provide a backing for the screws that hold up the vent interior bezel. Match the Bay to the position of the outside adapter that you are placing on the roof. If your air conditioner unit requires a larger hole please reach out to Kim 541-49O-4292 Outside adapters can be found here: https://www.ebay.com/itm/142478235445 or https://www.ebay.com/itm/133341703183 The strips come unassembled. The strips are glued in with 3M Window Weld or Sikaflex 221. The strips should be spaced out from the hole approximately 1/4". Check out our other items! Van owner and/or installer assumes all risk associated with roof top mounted items and/or components. Van owner and/or installer recognizes and agrees that this product, and each of its component parts, is sold ?as is? and that seller makes no representation or warranty of merchantability that the product is fit for any particular purpose.