"You should buy this Air Box Complete 1st Stage Air Filter"

An airbox is an empty chamber on the inlet of most combustion engines. It collects air from outside and feeds it to the intake hoses of each cylinder.

The airbox allows the use of one air filter instead of multiple filters thus reducing complexity. Developments arising from concerns about engine emissions during the late 1970s now allow the airbox to collect gases from the crankcase and the tank air vent and re-feed them to the engine.