The EHEIM Fine Filter Pad for the eXperience 350 is a premium replacement pad designed for both mechanical and biological filtration in the eXperience 350 external canister filter. This white fine-foam cartridge captures very small suspended particles and provides an ideal surface for beneficial bacteria to establish, supporting stable water quality and clarity. It is reusable through gentle rinsing to preserve the bacterial colony, and should be replaced when deterioration or clogging affects flow. Suitable for freshwater and marine aquariums.