Fluval Water Polishing Pads are specially designed to fit Fluval FX5 & FX6 High Performance Canister Filters. These extra thick, micro-fine polyester pads effectively trap micro-particles and debris as water passes through. Fluval Water Polishing Pads are ideally used when cloudy water occurs or after tank maintenance to provide crystal clear aquarium water. For freshwater and marine environments. Three filter pads in a pack.