Compatible Model The G52 Relief Valve Housing fits Zodiac Polaris 180, 280, 380, 480 PRO, 3900 Sport, Vac-Sweep 380, Vac-Sweep 280, 280 TankTrax models. Upgraded VersionCompared to the previous relief valve, our g52 relief valve replacement kit for polaris has upgraded shell material, crack-resistant polymer construction, won't be easily damaged and has twice the lifespan. G53 gear mechanismMade of stable and friction-resistant POM material. Pom has a very low coefficient of friction and good geometric stability, particularly suitable for the manufacture of gears and bearings, this material is better able to withstand high water pressure operation. FunctionThe upgraded version will solve the problem when your pool cleaner is stuck on an obstacle, although your emergency valve is still open, water will no longer be sprayed from the nozzle and will keep the water inside. 'exterior. Improved version Our g52 backup valve replacement kit for Polaris upgraded shell material, patented high strength and crack resistant polymer construction, won't be easily damaged. G53 gear mechanism Made of friction-resistant and stable POM material. Pom has a very low coefficient of friction and good geometric stability, this material is more able to withstand high water pressure operation. Function The upgraded version will solve the problem when your pool cleaner is stuck on an obstacle, although your relief valve is still open, water will no longer spray from the nozzle and prevent water from entering.< /p>