Microfiltration Technology: Spring-loaded filter cartridges are designed to trap larger debris and allow fine debris to pass through to prevent cartridges from clogging as quickly when the pool is particularly dirty [Multi-Version Compatibility] Fiitzn water filter perfectly compatible with the following Dolphin Robotic pool cleaners: Nautilus CC Plus, Oasis Z5i, Aquarius XL, Odyssey, C3, C4, Sigma, M200, M400, M500, M4, M5, Bio, Triton Plus (old), Liberty, Wave 65, and Wave 90. Part number: 9991433-R4. [Durable] ABS plastic frame, more sturdy and durable. It firmly supports the filter layer and prevents it from breaking during work. [Dimensions] 26.5 x 16.5 cm each, package includes 4 pieces, same as original model number 9991433-R4. Installation: If used correctly, these ultra-fine filters can last 2-3 years. Please rinse the filter every 4-6 weeks for optimal performance.