Airline-style 3″ metal swivel vents are available in clear or black anodized finish. Utilizes a large opening which is very effective in warmer climates. Designed to directly replace the black plastic vents that do not seal well when closed. Simple operation by pushing and turning the knurled barrel counter clockwise to open and clockwise to close. Weighs 5.5oz. Dimensions: 3″square, 2-1/2″ mounting hole pattern. 1-7/8″ opening, 30% larger opening than black plastic vents Precisely CNC machined, 6061-T6 aluminum. Seals well when closed, which is important in cold climates.