Compatibility: G52 backup valve for Zodiac Polaris 180, 380, 280, 480 PRO, 3900 Sport, Vac-Sweep 380, Vac-Sweep 280, 280 TankTrax pool cleaner. New Upgrade: Compared with the previous backup valve, we have upgraded the shell material to crack-resistant polymer blend, which is more wear-resistant than the previous product, will not be easily damaged, and has a service life twice as long. Fix the problem: When the pool cleaner is stuck on the obstacles or edges and is difficult to turn, or even if the backup valve is still open, the water no longer sprays from the nozzle, it is time to consider checking or replacing, we will update the product later will avoid this situation and avoid water stagnant.