This 9991425-R4 Ultra Fine Cartridge Filter Panel is for use with Maytronics Dolphin Robotic Cleaners. Designed for 21st-century pool owners, meet our smartest, most advanced robotic pool cleaners, here to deliver a whole new level of pool cleaning performance. Each Dolphin model is masterfully crafted to provide incomparable pool scrubbing and cleaning, with a cutting-edge water filtration system, and the best warranty on the market.