Green Label Parts air filters are designed with a special foam pre-cleaner, for use specifically in Cummins Onan RV Generators. Other manufacturers' air filters may contain a lighter density filter paper and the sealing surfaces may get brittle and crack over time, allowing dirty air into the engine intake system. Over time, it only takes about a thimbleful of dirt to wear out piston rings and cylinders. Please refer to your Operators Manual for specific maintenance intervals.