It has been so long ago since I ordered the plane kit and I don't have my packing list close at hand, but I believe the two air filters came as part of the Searey supply. They definitely did not come with the Rotax engine. Anway the install was easy, just slip over the carbs' inlet nozzles and tighten the hose clamps. Not mentioned in the Searey manual, but shown in the Rotax installation manual, is the installation of a safety wire. There not being a hole for such a purpose in the filters I just drilled one and wired each filter to a protuberance nearby on each carb.