Seal the top UV housing unit of your pond filter with the genuine Laguna Pressure-Flo UV-C Head O-Ring (PT1530 / PT-1530). Designed for Laguna Pressure-Flo 700 (PT1500), 1400 (PT1502), 2100 (PT1504), and 3200 (PT1506) pressurized filters, this high-grade elastomer O-ring seats into the upper UVC head module to prevent water leaks around electrical components and internal ballast connections.