Deep Blue Professional ADB88791 BioMaxx Power Filter Cartridge, Medium BioMaxx power filter cartridge is the ultimate in performance and convenience The multi-layer polyfiber outer shell traps debris and organic particles The premium carbon inside absorbs dissolved contaminants, odors, toxins and discoloration The rigid frame incorporates a media-grid design that ensures even distribution of the carbon granules The BioMaxx medium cartridge fits BioMaxx 10 and 30 filters and also fits Tetra Whisper and Top fin power filters too