If you do not have a 5.5" diameter air cleaner or you aren't in love with the one you have... If you want the hot rod style of the Defender or the F1 and increased air flow performance, Brass Balls Cycles offers both air cleaner covers with the S&S Stealth air cleaner kit. This S&S® Stealth air cleaner kit fits Big Twin and Sportster models. Increased filter area, combined with an air horn like radiused inlet and unique S&S® stinger cone to allow smoother faster air flow for more power. Kit includes back plate, filter element, top cover, hardware, and instructions. The Defender and F1 covers are machined from billet aluminum, black anodized or raw finish with carbon fiber inlay.