PondMaster 500 dual pond filter. Low profile, less obtrusive in the pond. Features a larger filter for less cleaning. Offers mechanical, chemical, and biological filtration. Filter media is easily changed. Quick disconnect for easy removal from pump. Can be used with many submersible pumps. 9 In. x 9 In. filter box with removable filter cartridge. For use with pumps up to 500 GPH (gallons per hour). For in-pond use only.