A trouble-free biological filter designed with adjustable 1" dia. uplift tubes for better water circulation and multi-plate constructionf or easy installation. Includes airline tubing and Discard-A-Stone and features the fish-saver elbow. Advanced design allows a separate plate installation and also has optional flow-thru set-up for use with a power head. Made f special quality plastic which resists splitting and creaking. available in three different styles to fit rectangular, hexagonal, octagonal, and flatback aquariums.