Kohler Genuine Part Gp1059291 Canister Seal - Pack 2

It fits so well with my toilet.

According to online information, Kohler developed this yellow seal to be a far more durable one than the original red seal. Only time will tell how well it holds up. It was a snap to install -- under five minutes. (Note: If you cannot remove the central unit as per the printed instructions, which was a problem I encountered, cut off the old red ring and unhook the chain connector. Then the new seal can be gently stretched over the outer cylinder and quickly snapped into position under the tabs in the lower edge of the cylinder. Return the chain hook to its original position.)