Ready-to-use cartridges for simple and convenient filter maintenance. Marineland Eclipse System Filter Cartridges feature a double-thick polyfiber pad on one side that efficiently traps dirt and debris. The other side features a patented ribbed backing for even distribution of aquarium water through the cartridge. Super-effective Black Diamond Carbon inside the filter cartridge quickly removes discoloration and dissolved organic pollutants. The result is superior mechanical and chemical filtration to maintain ideal aquarium water quality