This vent fits into a recess 218mm x 167mm, and has a mounting frame of 24mm beyound that. Features The frame and springs require just 10mm clearance below the outside face that they are mounted to, and the supplied internal finger grip extends just 18mm below the outside front face. These vents open to 30 degrees and therefore extend 120mm above the outside face that they mount on. They give a positive dust proof seal when closed. They do NOT include a flyscreen. Specifications 218 x 167mm.