K&N Custom Assembly Filter Kits utilize an adapter or tube that mounts directly to the air box. This universal clamp-on air filter then attaches to the adapter or tube. The large mounting surface of the clamp-on air filter provides better stability during rigorous riding. The assembly adapter or tube acts as a velocity stack within the air box. K&N Custom Assembly Filter Kits, like all K&N air filters, are designed to provide excellent filtration and outstanding air flow. Comes with aluminum billet adapter. Filter clamps on to adapter. Washable and reusable. High air flow with excellent filtration. Filter Specifications: K&N part number: YA-7006. Air filter shape: Round straight. Filter material: Cotton gauze. Flange inside diameter: 2.5 inches (64 mm). Flange length: 0.625 inches (16 mm). Flanges: 1.