One of the best products from master customizer Arlen Ness. These pure and simple performance air cleaners for Big Twins and Sportster mount under your stock cover (unless otherwise noted). They feature an all-in-one, cast aluminum backing plate, plain or chromed, with built-in carb support and breather tunnels to each cylinder head. Each tunnel exits at the mouth of the carburetor to create a virtually closed loop system without messy oil hoses and fittings.