The advanced Tetra CR Ceramic filter rings are designed for use with the Tetra external filter EX 400, EX 600, EX 700, EX 1200 and EX 2400, but can also be used with all other external filters and filter systems. Hollow ceramic filter rings with high internal surface area mechanically remove large particles from the water. Ceramic filter rings distribute water flow in a number of directions ensuring that water passes evenly through the filter. Tetra CR Ceramic filter rings can be used several times. Content: 800 ml.Do you have questions about this article ?