ZBK Series Fine-bubble Disk Diffuser is premium and durable, newly developed based on 30+ years of dedicated research and practice. The special membrane-tray self-sealing structure eliminates air leakage. EPDM membranes are treated by special refining processes, scientifically mixed with special anti-microbial and anti-aging materials, and manufactured by large automatic vulcanizing machines. Membranes are resistant to heat, ozone and weather, which are chemically stable and can operate in sewage for over 10 years.