... years. (2)Own facotry (3) pass SGS,ROHS test Water filter sponge:Filter sponges are widely used for aquarium filter,air filter and ... used to remove foul and peculiar smell, purify environment with high efficiency, low air pressure and low consumption. ... 1) Have numerous micro-pores. (2) Large surface area. (3) Excellent absorption. (4) Purifying ability.(5) Eco-friendly product. Water filter sponge