Polaris Zodiac 180 280 380 3900 Backup Valve Mechanism (G53) circuitbreakers A properly selected replacement helps A properly selected replacement helps preserve the intended fit and finished appearance of the valve instead of forcing the repair to rely on a substitute that only partly fits The after 2003 model compatibility and quantity of eight format give this set practical value because sand filter internals work best when they match the original model generation and quantity relationship closely Replacement backup valve mechanism for 180 280 380 3900 applications helping the cleaner maintain reliable movement throughout the pool