The EHEIM Coarse/Fine Filter Pad for the eXperience 350 is a dual-layer foam cartridge crafted for mechanical and biological filtration in external canister setups. The coarse side traps large particles and debris, while the fine foam offers increased surface area for beneficial bacterial colonisation. Designed for reuse through rinsing (rather than replacement) to preserve biological media, it maintains clear water flow and supports a stable aquarium environment for both freshwater and marine systems.