The Korky 2x long-life toilet flush valve seal fits Mansfield 210 and 211 standard 2-inch flush valves and replaces the Mansfield rigid flapper seal. The proprietary chlorazone ii rubber formulation lasts 2 times longer than other seals and is backed by a hold-up in the harshest environments. Korky red rubber resists chlorine, bacteria, city water treatment, hard water, and well water.