Replacement Cap O-Ring for Lifegard Aquatics AF Mechanical Filters, Chemical Filters & Heater Modules and QL-15 to QL-40 UV Sterilizers . 4" diameter. Lifegard Aquatics part # 220001.
Lifegard Aquatics recommends you coat the O-ring with Lifegard Aquatics Silicone O-Ring Lubricant .
