Sea-Doo Jet Pump Wear Ring (139.5 MM) SP/GT/XP/GTS/GTX/Explorer/SPI/SPX/Speedster/HX/GSX/GTI/Challenger/GS/Sportster 271000290 The SBT wear ring performs better and is more economical, which allows you to replace the wear ring every time you are doing work on the jet pump. Will only work with plastic housing NOT alluminum. SBT has engineered our replacement Seadoo wear rings for reduced friction using one hundred percent Delrin instead of fiberglass filled plastics. The Delrin wear rings have very low water absorption and are chemically resistant because they are acetal based plastics.