Large exit dome allows greater air circulation. Vent opens easily and holds any position. Easy to install with a one-piece plastic ceiling trim with radius corners which adjusts to fit roofs from 1" to 3" thick. Lid, screen, and crossbar assembly opens out in seconds for emergency escape. Fits cutout size 26" X 26" size. For installation products see categories “Roof Vent Accessories” and “Roof Coatings.”