Compatible ModelG52 Relief Valve Housing fits Zodiac Polaris 180, 280, 380, 480 PRO, 3900 Sport, Vac-Sweep 380, Vac-Sweep 280, 280 TankTrax models. Upgraded VersionCompared with the previous relief valve, our g52 relief valve replacement kit for polaris has improved shell material, crack-resistant polymer construction, won't be easily damaged, and lasts longer. twice as long life. G53 Gear MechanismMade of stable and friction-resistant POM material. Pom has a very low coefficient of friction and good geometric stability, especially 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 keep the water out.