Rio Cut-to-Fit Poly Filter Pad 18x10This cut to fit aquarium filter media pad is made of durable polyfiber material perfect for aquarium use. These can be used in any type of filter or sump. The structure of the Cut to fit polyfiber filter is ideal for removing free floating particles. Removal of waste from aquarium water not only clarifies but also eliminates pollutants before they deteriorate into toxic chemicals. 18" x 10" Easy to cut and fit in filter cartridges Traps micro & macro