A black, spiral-shaped plastic media designed for filtration in aquatic systems. Loose fill media fits into ANY-shape container or filter: upflow, downflow, trickling, pressurized, rotational, etc. LARGE surface area for beneficial bacteria growth: approximately 95 sq ft of surface area per cubic ft. VERY easy to clean .. simply rinse off. Will last for Years! Each cubic foot of media is packaged in a black nylon mesh bag.