This biological filter has a multi-level plate design. The larger plate sizes reduce the number of plates required. The added strength of the UGF plates makes this filter most preferred by saltwater aquarist. The molded gravel guards eliminate the possibility of gravel falling down the uplift tube. Includes Premium Carbon Cartridges, Slim Discard-A-Stones, telescoping ring for uplift tube height adjustment and Lee's fish-saver elbow. Made of special quality plastic which resists splitting and cracking. •12" x 24"