AC Infinity claims the Hydrone7's intake adapter is optional, but their filter is literally attached to it.  Without it, the filter has no where to live.  If you're running the unit without a duct hose, that means either going filter-less (not recommended) or using their huge filter duct adapter and having it eat up all your space, add noise, etc.  This low-profile print holds the intake filter directly on the unit.  No more adapter/duct.  Full flow, less noise, and no wasted space. 