Dolphin Maytronics Replacement Cartridge Fuilter Kit, Ultra Fine Filter Cartridges for use the in the basket style cleaners, see models below. Used on the following Dolphin Maytronics Cleaners: Dolphin Triton Plus with PowerStream Dolphin Triton with PowerStream Dolphin S300i Dolphin S300 Dolphin S200 Dolphin Active 20 Dolphin Active 30 Dolphin Active 30i Dolphin Prowler 920 (Pentair) Dolphin Prowler 930 (Pentair) Dolphin Quantum, Dolphin Discovery, Nautilus CC Pro