Check the listing for details. Maxxair Dome Adapter for Sprinter High Roof. Color: Black, Condition: New without tags. Listed at 5.00 USD. Center and Off Center is in reference to the center line of the roof. The off center measurement is from the center line of the van to the center of the hole. In some cases we talk about it being center on rib 1 or rib 2. For this please treat the center rib on the center line of the roof as "0", next rib over is "1" and the next is "2". Normal 0 false false false EN-US X-NONE X-NONE Patent Pending adapter matches the contour of the OEM roof so the Maxxair Dome mounts to a flat surface. Prevents distorting the roof sheet metal or vent flange and can be used as an aid for locating the fan. They are CNC machined out of UV and fire resistant expanded PVC. The fan mounts to the outside adapter. The adapter ID is 7" and the OD is 10.5" Inside Backing frames are flat with not ribs. If you have questions about this product you can call Hein at 541-49O-5O98 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.