YEE YFM-026 White Respiratory Biological Ring 500g Aquaponics Porous High Performance Micropore Bacteria Filter Ring - Small white cylinder with fine micropores Dimension*: Length: 1.5cm; Inner Diameter: 7mm; Outer Diameter: 1.5cm *Estimated figures. - High temperature sintered far-infrared bio ring - Do not decompose, seawater corrosion resistance - Regulating water quality, purifying water by nitrifying bacteria and with fast decomposition of nitrite - With fast and strong adsorption of water impurities - Reduce the frequency of fish tank water exchange