This is the 4.25 cu.ft. AquaBead or AlphaONE unit. What a nice size filter. A 4.25 cu. ft. capacity designed to be used on ponds up to10,000 gallons with fish loads up to a whopping 225 lbs. That's a lot of fish. Easily flows 90 gpm while only having a footprint of 24" X 35.5".