The Korky 2X Long-Life Toilet Flush Valve Seal Fits Kohler Toilets. Designed to replace the original seals on Kohler AquaPiston, Class Five, and Class Six toilets. Replaces original Kohler Seal: GP1059291. The proprietary Chlorazone II rubber formulation lasts 2 times longer than other seals and is backed by a 10-year warranty to hold up in the harshest environments.