This is an authentic Hitachi replacement part, sourced from the original manufacturer for use with air compressors. The special cover is used to seal the side of the carter that houses the crankshaft. This cover is available as an individual replacement part, please see model diagram for associative parts.
This part is an OEM from Hitachi. The intake filter housing is made for use with several air compressors. This plastic component fastens the filtering element to the head filter plate, and is sold individually. A screwdriver is needed for the removal and replacement.