Description: Item Type:Sponge Material:Cotton Color:Black Feature:Durable Size:50 cm/19.69"*12 cm/4.72"*2 cm/0.79" Features: 1. High Shading: the moderate elastic density has good shading and can reduce algae breeding. 2. Bacteria Nitrifying: the moderate size of pores are conducive to the cultivation of high-density nitrifying bacteria. 3. Filter: the biochemical cotton has the best effect on decomposing excrement and feed residue, improving water quality and reducing the mortality of fish. 4. Thickened Fabric: it is durable and high water permeability, and it is more effective decomposition of impurities in water. 5. Economic: compared with the common sponge, this biochemical cotton sponge is washable and can be used repeatedly. Package Include: 1 x sponge Notes: 1. Please allow 1-3 cm difference due to manual measurement and 3-5 g for the difference between different colors. 2. Due to the screen difference, the color may be a little difference from what you expect, please allow it. High Shading: the moderate elastic density has good shading and can reduce algae breeding Bacteria Nitrifying: the moderate size of pores are conducive to the cultivation of high-density nitrifying bacteria Filter: the biochemical cotton has the best effect on decomposing excrement and feed residue