The all new Walker Performance Filtration Airbox. It replaces the competitors box and actually seals and keeps dirt out of the engine. This is an 80% filtration improvement over the competition. It has a soft polyurethane sealing surface to ensure complete sealing all the way around the box. It comes with the cartridge and the lid. The cartridge can also be purchased separately and is easy to replace. The cartridge folds flat for storage and makes washing very easy.