Large exit vents admit three times more fresh air than conventional-size dome vents. Vents open easily with either opening mechanism and hold at any position for air control. Available in opaque white with aluminum frame and four piece metal garnish, cut to roof thickness. Includes white plastic, leak resistant lids. #31-1829 has a plastic frame with 2-7/8" plastic garnish. #31-1827, #31-1803 and #31-1822 have metal frames with four-piece 2" white metal garnishes.