4-PK Marineland Penguin Power Filter Cartridge, Rite-Size A, 1 Count Each. Condition is “New”. Shipped with USPS First Class Mail. (V6)

From Manufacturer:

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.