Features: The external carbon dioxide Refiner effectively filters water, providing clean and healthy water quality. Use selected corrosion resistant stainlesssteel material, this Refiner maintain its shape even after extended use, ensuring durability. Great for those who love keep fish, shrimp, and other creature, it create a great environment in their fishtanks. Conveniently installed outside the Fishtanks, it space saving and is easy adjusting and maintain, ensuring a clean environment inside the Fishtanks. Great for various water facility in petstores, it help maintain a balanced ecosystem and showcases quality fishtanks environment. Specifications: Material: StainlessSteel Style Option: 01(Small, 15cm)/02(Small, 20cm)/03(Medium, 15cm)/04(Medium, 20cm) Product Size: As pictures shown Package Includes: 1x Fishtanks External Refiner note: Please allow 1-2cm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actualcolor of the item.