Our fixed E-Class model (EF) is ready to go right out of the box ? no mastic, no step-flashing, no sealants. Our one-piece curbframe and flashing design cuts 90 minute installation to 30 minutes!1?Plus, Wasco E?Class skylights deliver up to 22 percent more daylight!?Our E?Class self-flashing skylights sit directly on the roof deck, giving you a larger glass area per rough opening compared to competitor. Wasco?s E-Class skylights feature condensation control without the use of weep holes for maximum energy efficiency. Wasco?s thermally broken vinyl curb frame incorporates a large condensation channel that collects condensation until it can naturally evaporate, eliminating the need for drainage weep holes that allow outside air to pass through the curb, diminishing the energy efficiency of the skylight. Rough Opening: 22.5" X 46.5". Daylight Area: 21.125" X 45.125". Daylight Opening (Square Feet): 6.61