All Penguin Bio-Wheel Power Filters deliver easy, three-stage mechanical, chemical and biological aquarium filtration. Convenient Penguin Rite-Size Filter Cartridges come ready to use with each filter... ready to mechanically and chemically remove waste, discoloration and odors. Each contains new faster-acting Black Diamond Premium Activated Carbon for maximum efficiency. Biological filtration is provided by the revolutionary and patented BIO-Wheel - proven best at removing toxic ammonia and nitrite. All BIO-Wheel filters feature Noise-Reducing Two-Piece Vented Covers, and Adjustable Mid-Level Intake Strainers. Pro Series Features: 1) Dual impellers for extra power. 2) BIO-Wheel Technology. 3) Ready-to-use filter cartridges. 4) Total water circulation. 5) Additional media slots to increase filtration.