Zodiac Jandy AquaLink RS4 PCB Pool/Spa Rev QQ (R0466806) senasys An O-ring like this is

An O-ring like this is useful because it helps keep the inline union leak-resistant while preserving the serviceable nature of the connection for future maintenance

connection-specific filter elements

or damaged during filter or valve work

or worn filter parts

Zodiac Jandy AquaLink RS4 PCB Pool/Spa Rev QQ (R0466806) senasys An O-ring like this isBreather tube for zodiac aquapure ei chlorine generator maintenance is built for targeted repair where the correct fit matters more than a generic workaround. This tube supports proper system function within the Ei assembly and is useful when original tubing becomes brittle, clogged, or damaged. It should be matched carefully to the AquaPure Ei model and part number. The part is especially useful for keeping compatible pool, spa, or equipment pad