Check the listing for details. ATI Hydro Sponge PRO Filter Size # 2 Course Aquarium. Condition: New. Listed at 20.49 USD. ATI Hydro Sponge Filter #2 Listing is for ( 1 ) : ATI Hydro Sponge PRO Filter #2 Course NOTE: These filters are " Brand New " and authentic ATI Hydro Sponge filters but they are not shipped in a "Retail Box ". *Redesigned aquarium sponge filters for improved bio-filtration*Use reticulated foam filter with higher flow rate powerheads*Beneficial bacteria colonize sponge filter for waste breakdown Reticulated foam sponge filters enhance aquarium biological filtration. Hydro-Sponge Pro Filters are upgraded to double the efficiency of the popular ATI Hydro-Sponge Filter. Versatile reticulated foam sponge filters handle higher flow rates without clogging, making it the ideal choice for use with aquarium powerheads. Durable reticulated foam is longer-lasting and is easier and faster to clean to ensure reliable performance. Hydro-Sponge Pro Filters provide both mechanical and biological filtration. Raised filter sponge maximizes surface area exposure to optimize bacterial colonization and efficient breakdown of toxic ammonia and other nitrogenous waste. Weighted base allows for easy placement while preventing drifting. Use with an air pump or attach a powerhead to the included one inch diameter lift tube to suit your filtration needs. Modular design allows for stacking of multiple units to increase filtering capacity. For aquariums up to 20 gallons. Sponge size 4 x 2.75 inches NOTE: These filters are " Brand New " and authentic ATI Hydro Sponge filters but they are not shipped in a "Retail Box ". Please feel free to contact me for International and combined auction shipping rates or with any questions or concerns that you may have about my products. Thank you !