Parts - 9991432-R4 Ultrafine Filter Cartridges for Maytronics Dolphin Pool Robots, Compatible with Delphin Nautilus CCPlus, M400 and M500. Product Features: 1. Ultrafine Filtration: Pleated filter media is used to filter all types of ultrafine debris in the pool, such as fine sand, algae, leaves, etc. 2. Durable and Strong: ABS plastic frame, stronger. Properly applied, these ultrafine filters can last 2 to 3 years. Compatible Models: For Delphin Nautilus CCPlus Filter. For Maytronics Dolphin Parts 9991432. For Delphin M400 M500 Filter. For Delphin M4 M5 Pool Cleaner. For DolphinOrion, Deluxe3, Atlantis, Apollo, ApolloPlus, DX3, DX3s, DX4, DX4s, Sigma, Odyssey, OasisZ5i filters. Product Features: Dimensions: 10.43 in x 6.3 in Package: 4-pack filters for Dolphin robotic pool cleaners. Tips: 1. Please rinse the filter every 4 to 6 weeks for optimal performance. 2. Always follow the filter's user manual when changing filters.