The Large Spring Cartridge Filter Panels are designed to only trap larger debris and let fine debris pass through to prevent the cartridges from being clogged as quickly when the pool is especially dirty, for example when you open the pool in spring. The set includes four large cartridge filter panels. Filters are for use with specific cleaners including Dolphin Triton, Nautilus, Dolphin Wave 75, Dolphin Edge, Dolphin Quest, Dolphin Premier, Pentair Prowler 820, Pentair Prowler 830. The Spring Filters can also be used in Dolphin Pool Cleaners that have the 9991414-R1 conversion kit: Dolphin Deluxe 4, Dolphin Deluxe 5, Dolphin DX6, and Dolphin Discovery.