Marineland Rite-Size Cartridge K - 12 Total Cartridges (4 Packs with 3 per Pack) 12 Total Cartridges (4 Packs with 3 per Pack) Marineland Rite-Size Cartridge K There's a Rite-Size cartridge for every Penguin, Emperor, and millennium power filter Is designed specifically for horizontal placement in our extensive selection of Eclipse systems Color-coded packaging ensures fool-proof cartridge selection Delivers crystal clear, crystal clean water