Stainless Steel Roof vent with Battery backup.  8.5 inches in Diameter. Unlike other cheaper fans for sale on eBay the power switch is readily accessible. No need to stop the blade to reach inside switch on or off Also no loose battery issue. fan also comes with inner trim ring. Requires a 4 1/2 inch hole to install. New in Box. $12.95 to ship in USA. Please contact me with any questions you may have. I ship items Very quickly often same Day. Thanks for looking here!