13 pcs filter sponge:10 pcs 2cm filter sponge & 3 pcs 2.2cm filter spongeKeep your water clean and clear with the replacement bio sponge for use in the Cascade 600 GPH Model CIF3 Internal Filter.Filter sponge optimizes the colonization of beneficial aerobic bacteria which prevents the water from becoming cloudy and harming fish.Cascade 600 GPH Internal Filter Bio Sponge keeps the water in your aquarium clean and clear.This Cascade filter removes ammonia and nitrites from the water keeping your fish tank healthy; clean; and odor free.Usage Range: Fit for every size fish tank or pond.Provides biological and chemical filtration and increase the oxygen solubility in aquarium and fish tank. Dense honeycomb shape makes it effective to avoid residue and reduce the death rate of fish.This bio sponge also optimizes the colonization of Beneficial aerobic bacteria which prevents cloudy water and excess CO2 which can harm.Made specifically to fit the Cascade 600 Internal Filter; this replacement bio sponge fits securely without gaps that lead to vulnerablees in filtration strength.An exact fit keeps debris and contaminants from getting through Your filtration system and back into water.Made of a durable -fiber; this bio sponge filter is made to last for several months under normal conditions.When used together; the Cascade 600 Internal Filter Model CIF3 and Cascade 600 filter cartridges provide maximum protection.Against water pollutants from harming your fish.size: Length: 8cmDiameter: 4.5cmProduct Name: Filter SpongeColor: BlackMaterial: Sponge + biochemical cottonSize: 8x5cm()Inner Hole Dia: 2cm/0. 8 inch + 2.2cmTips:1. You can cut the size as you need.2. A small rubber band can be used to close off bottom of sponge if strainer has openingson bottom.3. Can be used again after cleaning.Package Contents13 x filter spongeOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.