Korky Plus Classic Rubber Flapper with Chain is expertly designed to stay open longer, making it an i fit for older 5 and 7 gallons per flush (gpf) toilet models. This flapper features a collar that easily attaches to brass flush valves and can be removed for compatibility with plastic flush valves. Crafted from exclusive longest-lasting red rubber, it resists damage from chlorine, bacteria, city water treatment, hard water, and well water. The flexible rubber construction ensures a tight seal and simplifies installation, providing reliable performance and durability for your toilet. Model Number: