Fan-Tastic Vent has two non-powered vents that open manually and come equipped with Pop ‘N Lock screens. The non-yellowing ASA plastic vents are designed for exterior durability, the company says. The 800 dome model is opaque and fits a roof thickness of 1 in. and up. The 900 dome model is smoke polycarbonate, giving a skylight effect, and fits a roof thickness of 1.75 in. and up.