Standard width. K&N realized a +7 HP increase on the Dyno. The K&N RK-Series air cleaner assemblies are truly stealthy air cleaners since the stock air cleaner cover is re-used. Power increase is realized by replacing the stock filter and backplate. A special K&N powder coated aluminum backplate; with Dyno-tuned velocity stack; is required to house the oversized K&N air cleaner element. Built-in breathers replace the stock external breathers. Careful design made it possible to re-fit the stock air cleaner cover for a stock un-touched look. Includes a complete high flow assembly with backplate-filter combo; mounting hardware and a chromed plastic ''beauty ring'' with ''K&N'' and ''High Flow'' engraved. Includes installation hardware. Note 1: Reuse OEM chrome oval air cleaner cover. Note 2: Will not fit in combination with OEM round air cleaner covers. Note 3: Extra wide element will not fit completely under stock cover. Note 4: Will not fit 99-01 FLT/Touring with Magneti-Marelli fuel injection system. Note 5: See 900336 X-wide kit. Or see 900337 for the extra wide (57mm high instead of 44mm) filter element to convert this 900311 air cleaner assembly; complete with offset spacers; for even more air flow.