Made of advanced PET materials, standard pure 304 stainless steel core not rust. Can absorb suspended substances in water on a large area, and promote the growth of nitrifying , swallow harmful , thus achieving biological and physical filtration effect The air, water and biofilm can be fully mixed and infiltrated to exchange, reduce noise, and disperse the momentum of water flow. Biofilm can not only implant evenly on each silk strip, maintain good activity and interspace variability, but also gain more and more specific area in the process of operation, and have a good metabolism. Product name:Fish tank aquarium filter brush Type: fish size: 40x12cm Material:PET+stainless steel colour:black Package Contents: 10 x filter brushes Only the above package content, other products are not included. Note: Light reflection 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.