The Rheem RTG20299AG O-Ring P-20 is a critical sealing component for Rheem tankless water heaters. This O-ring is designed to provide a reliable seal, preventing leaks and ensuring the efficient operation of your water heating system. Made from high-quality materials, it is resistant to heat and wear, ensuring durability over time. The P-20 size is compatible with various Rheem models, making it an ideal choice for replacements. By using this O-ring, you can enhance the performance of your water heater and maintain compliance with installation standards, ensuring a safe and efficient system.