Dome Dimension: 20-1/2' x 19' x 4-1/2', Flange Dimension: 24-1/2' x 23' Made of durable, impact resistant polycarbonate Industry leading quality skylight - Thicker and stronger than the original OEM skylight Take the dimensions of your skylight opening on your RV and compare them with this skylight to ensure a proper fit for your unit Use ICON Skylight Sealant for install