The fits Kohler class five 3 in flapper toilet Tank flapper is designed to fit Kohler parts: 1016546 and 1042313. The exclusive longest lasting red rubber resists chlorine, bacteria, city water treatment, hard water and well water. This is a large 3-1/4 in replacement toilet flapper designed to fit rectangular, black flush valves. Made of flexible rubber for a tight seal and easy to install.