The illustration of the MD32A on the Volvo Penta site looks exactly like my AQD32As. These do not have replaceable air filters. As said above, there is just a fixed metal gauze at the top of each of the three trumpets on the intake box. This can be cleaned but should not need doing very often. I used a steam cleaner on mine as they were clogged up with fluff when I bought our boat but have not bothered since.