K&N Recharger kit contains K&N air filter cleaner and air filter oil. It is a six-step maintenance system designed to recharge any K&N FilterCharger air filter. Air filter oil is used to treat foam air filter elements to increase their filtering capacity. Red filter oil helps to extend engine life and prevents dirt from entering your engine. Air filter oil boosts the performance of cars and trucks. K&N air filter cleaner is the only cleaner formulated to clean K&N FilterCharger elements. K&N air filter cleaner works to dissolve the dirt build up and old filter oil, and can be washed away with water. It is biodegradable and safe on paint, chrome, cast aluminum, plastic, rubber and vinyl when used as directed. Complete instruction is included with this kit.