K&N offers replacement air filter kits for UMP's 3" & 4" Off-Road Air Intake Boxes. These air filters were designed to achieve high, virtually unrestricted airflow while maintaining filtration levels critical to your engine. These filters use the same oil cotton gauze technology, instead of UMP's standard disposable paper filter. The kits come with the pre-oiled filter, mounting bracket, pre-filter, & sealing grease.