Compatibility: G52 Backup Valve for Zodiac Polaris 180, 380, 280, 480 PRO, 3900 Sport, Vac-Sweep 380, Vac-Sweep 280, 280 TankTrax Pool Cleaners. New Upgrade: Compared to the previous backup valve, we have upgraded the housing material to a crack-resistant polymer blend, which is more wear-resistant than the previous product, is not easily damaged, and has a service life twice as long. Troubleshooting: If the pool cleaner gets stuck on obstacles or edges and is difficult to turn, or even if the backup valve is still open, water no longer sprays from the nozzle, it is time to consider an inspection or replacement. We will update the product later to avoid this situation and prevent water damage stagnates.