This aircleaner fits S&S 4-1/8" bore engines with vacuum breathing cylinder heads for 1984-'16 HD big twins. Uniquely designed back plate with air horn style radiused entryway and dimpled cover with directional air cone on inside creates smooth path for air to reduce turbulence. A performance air cleaner is a must to get the most out your engine. Kit includes, aircleaner backplate, pleated, washable filter element, chrome plated aluminum teardrop cover, all required hardware, and instructions.