K&N Universal Clamp-on Air Filters K&N universal air filters are designed and manufactured for a wide variety of applications. Regardless of the angle, outside diameter of the air inlet, there is a K&N universal air filter for your equipment. All filters are constructed with ultra-strong molded flexible rubber flanges that absorb vibration and allow for a secure fit and can also stretch up to 1/16 (1.5mm) to fit in-between sizes. K&N Universal Air Filters are available in round, conical (cone style) and oval designs, for almost any special application. Select a universal filter type below to see available sizes.