Dry-Foam Air Filter for 1-3/4 SU carburetors. The wide space wire mesh and dry foam elements offer superior air filtration with a minimum of attaching parts and fuss. Stamped steel and chromed backing plate mounts securely to each carburetor. Includes breather fittings. Filter elements are washable and reusable. Attaching hardware included. Backing plate is 5-1/2" in diameter. Replacement element is part number 17-0890.