Abstract: An interface air filter and assembly for use with an internal combustion engine is disclosed. The assembly has a housing having an air intake port and an opening. There is an air filter assembly with an air filter having a closed end and an open end and a reducing coupling. The reducing coupling has a first end with a first engaging member having an external circumference and outer surface, a second end with a second engaging member having an external circumference less than the first engaging member external circumference, and the second engaging member has an inner surface. The first end of the reducing coupling is attached to the open end of the air filter. The air filter assembly is in contact with the housing such that the air filter resides within the housing and the outer surface of the first engaging member engages the housing.