Features: RV Toilet Seal Replacement for Dometic 300 310 320 RV Toilet Gasket Flush Ball Seal Kit - Replace Part Number 385311658. Does Not Fit 210, 510 Or Any Other Models Not Listed. Our factory use original device to make molds making gasket fit perfectly. It will help you fix your problem and keep water in place. The sealing ring can keep water in place and eliminate odors effectively, effectively solving leakage issues. Made of high-quality rubber, it has higher durability and optimal quality, resulting in a longer lifespan. Effectively solve the problem of unpleasant smell and leakage caused by worn or damaged toilet seal, keep the RV environment clean and fresh. DIY installation saves money No need to hire a repairman, just follow a few simple steps to install successfully. Specifications: Material:Rubber Outer Diameter: 4 Inch; Inner Diameter: 2.75 Inch. Package List: 1x Gasket