Specialty Recreation SL1626S Skylight Dome Bri-Rus Skylight Dome. Skylights are made of high performance thermoformed polycarbonate to be long lasting and easy to clean. When choosing a Skylight, measure your rough hole opening as well as the overall exterior size. There is a size to replace most manufacturer's original equipment. Skylights sit directly on your RV roof. If necessary, an inner garnish is available to finish the inside hole (order separately). No metal flange is used with these single pane skylights. Use a skylight size that is equal to or greater than your hole dimensions. Note: inners must be the exact size as the hole you are working with. Skylights include care instructions, and include a tube of approved urethane sealant that must be used when installing. 60305 is a Rectangular Skylight, Smoke color. Hole size 16 inch x 26 inch; flange size 20 Inch x 30 Inch; height 4.5 inch.