Coarse mechanically working material is used where water first enters the filter process, Water is swirled and coarse particles of dirt sink, Then the water continues its way through the other filtering layers, Immediately after entry into the filter the water is swirled through this hollow ceramic material, Through this action the coarse dirt particles are removed, Eheim Mech is easy to clean and can be used several times, Size: 1 L, SKU: RPS12367