The Korky Ultra High Performance Flapper is the most universal standard 2 inch flapper available. The flapper adjusts to match original toilet settings and eliminates water waste by decreasing the amount of water flushed. Ideal for all standard 2 inch toilets, including: 1.28, 1.6, 3.5 and 5 gallons per flush gpf. The exclusive longest lasting red rubber resists chlorine, bacteria, city water treatment, hard water, and well water. Recommended by the Clorox help line, this Korky flapper is proven longest lasting. The adjustable flapper has multiple settings to ensure it fits popular standard 2 inch toilet models: American Standard Cadet 4029, 4078, 4083, 4053, 4650, Monarch 4003, Mainstream 4061, Evolution 2 Flowise 4061, Kohler Wellworth K-4620, Wellworth K-4519, and TOTO 706. Made of flexible rubber for a tight seal and easy to install.