REPLACEMENT FILTER CARTRIDGES: Fit Marineland® Penguin® Bio-Wheel® Power Filters. EASY TO INSTALL: Pre-assembled cartridges slide easily into place, providing superior mechanical and chemical filtration and making replacement fast, dry and effortless. OPTIMUM WATER-TO-CARBON CONTACT: Patented ribbed backing ensures even distribution of carbon for crystal clear, clean water. COLOR-CODED PACKAGING: Rite-Size™ packaging makes it simple to choose the right size replacement cartridge for your filter. MARINELAND FILTRATION PRODUCTS: Count on Marineland brand for the most reliable, technically advanced aquariums and accessories on the market.