Parts - Ultra fine filter cartridges 9991432-R4 for Maytronics Dolphin pool robots, compatible with Delphin Nautilus CC Plus, M400 and M500. Product Features: 1. Ultra Fine Filtration: Pleated filter media effectively captures various types of fine debris in swimming pools, including fine sand, algae, and leaves. 2. Durable Construction: Built with an ABS plastic frame for enhanced durability. With proper care, these ultra-fine filters can last 2-3 years. Compatible Models: Designed for use with Delphin Nautilus CC Plus, M400, M500, M4, M5, Orion, Deluxe 3, Atlantis, Apollo, Apollo Plus, DX3, DX3s, DX4, DX4s, Sigma, Odyssey, Oasis Z5i pool cleaners. Tips: 1. Rinse the filter every 4-6 weeks to maintain optimal performance. 2. Always follow the manufacturer's user manual when replacing filters.