1>sponge filter,good Aquarium filters 2>Aqua sponge, polyether foam materials 3>Reticulated;open cell(10ppi---70ppi) sponge filter,filter parts---filter sponge which widely used in aquarium filtering, water treatment, water pump, pond and so on ...The filter sponge has different mesh(8ppi-60ppi), high resilient ,good colors and good air permeability .Widely used for aquarium filter, water pump ...