Wilton Dome - DM9901-78https://www.crownmoldings.net/media/ecom/prodsm/wiltonround-sm.jpgClassic Ceilings Collection Wilton Dome (DM9901-78) -- Dome Dimensions: Dome Outside Diameter: 77-3/8 in., Dome Rough Opening: 75-1/2 in., Dome Opening Depth: 16-1/2 in., Dome Medallion Size: 18 in.Classic-Ceilings-Collection-Wilton-Dome-DM9901-780.00Classic Ceilingsin stockhttps://www.crownmoldings.net/Item/Classic-Ceilings-Collection-Wilton-Dome-DM9901-78