Before buying, please confirm that the part number and size you need match the model. accurate COMPATIBLE WITH: Polaris 3/4 hp(Pre 2012)Booster pump ， And more pumps with matching parts. ESSENTIAL COMPONENTS: Includes shaft seal O-ring replacement for O-30 P40, volute O-ring replacement for O-299 P95, and pump shaft seal replacement for PS-1000 AS-1000 U109-136SS. The outer diameter of the large ring is about 7.1inch, the outer diameter of the small ring is about 0.7inch, the shaft seal of the pump is about thickness 0.74inch x od 1.62inch, The shaft seal gasket is about 1.25 inches in outer diameter and 0.4 inches in thickness. O-Ring Replacement Pump Seal Repair Kit (Prior to 2012, Serial number before M12011001) . PREMIUM-QUALITY MATERIALS: Made from durable materials to ensure longevity and reliability, with precise engineering for optimal pump performance. EASY INSTALLATION: Simplified installation process with detailed instructions, making pump repair and maintenance hassle-free for pool owners