High performance polycarbonate skylights are virtually unbreakable and easy to clean. Replaces most original equipment. To determine size, measure outside flange to flange (2nd size listed below) and measure rough hole (1st size listed below). Each skylight includes a 10 oz. tube of sealant for installation. 1/box 

Falnge to Flange Measurment 17" x 25"

Manufacture Code: SL1422W