The Biocube premium filter cartridges feature dual-action filtration. The dense woven floss acts as a prefilter to clear detritus and debris while the activated carbon removes odor, organics and discoloration. The rigid frame ensures that water passes through the cartridge and not around it for optimal water filtration. – For use in BioCube Aquariums- models 14, 16, 29, 32 and HQI – Dense woven serves as a prefilter to remove organic waste and debris from water – Activated carbon removes odor, organics and discoloration from water – Contains 2 cartridges