Key Features Genuine Eden Part Replacement Foams for the 304 Internal Filter (Part 57543) Part No 57659 High Quality foam material 75 x 40 x 25mm Keeping your aquarium filter in top condition has huge benefits to the tank and the fish inside. Simply changing the filter foams on a regular basis helps to keep the filter in top shape. The longer a foam is used in a filter, the more it can lose its overall effectiveness to trap unwanted debris. When this happens your aquarium water may not appear as clear as it once was. The foams are made of a high grade material and fit easily into the relevant filter.