1. Fits 3" flush valve opening: The Hibbent toilet flapper fits for TOTO?3 inch oversize flapper which features an oversized sealing surface to fit for large 3-inch TOTO flush valves. 2. High-quality TPR material: flexible siliconized red rubber for a tight seal, long-lasting, resists chlorine. Specialized Red Rubber For Resisting City Water Treatment, Hard Water, and Well Water. 3. Compatible with Toto Flapper: Replacement 3 Inch Toilet Flapper compatible with Toto G-Max THU499S, THU175S & 2021BP. 4. Compatible with TOTO models: ST743S, ST744S, ST754SF, ST764S, ST774S, ST784SF, ST94SF, ST814S, CST756204SF, SCT853S, CST845S and CST874S. 5. Easy to install: Tools are not required for installment and are easy to replace. Includes 3" flapper and stainless steel chain with clip hook. Product Description Replacement compatible with TOTO flapper model THU138S, THU175S, and THU331S Compatible with TOTO Toilet Models: ST743S, ST744S, ST754SF, ST764S, ST774S, ST784SF, ST94SF, ST814S, CST756204SF, SCT853S, CST845S and CST874S. Please Note: Toilet flapper does not compatible with the following TOTO models: ST743E, ST744E, ST754E, ST784E, ST794E, CST853, CST853E, CST854, and CST854E. Easy to Install Toilet Flapper Color: Red Diameter:10cm/3.93inch Length of chain:32cm/12.6inch Flapper Material: Rubber Chain/ hook material: stainless steel