Fluval fine filter fleece pads are uniquely designed to fit Fluval cansiter filters. These extra thick micro-fine polyester pads capture micro particles as the water passes through. Use Fluval fine filter fleece pads when cloudy water occurs or after aquarium maintenance for crystal clear aquarium water.Fluval Fine Filter Fleece FX Series+ water polishing pads+ effectively traps micro particles and debris+ for crystal clear aquarium water+ for freshwater and marine water enviroments+ rinse frequently, replace after 1-2 months+ for Fluval External Filters FX4/5/6+ Package content: 3 pieces+ Fluval No. A246