Review on 🔧 Toto THU123 Replacement Valve Cap Assy: Top-Quality Solution for Optimal Performance by Mike Anderson

According to Korky and Toto Support, Korky R528 should work the same as a genuine Toto part for Toto Aquia CST645MF with DuaMax filling system. You are both wrong. THIS part is the original Toto part that works while the Korky part works (the fit is slightly tighter resulting in no flow with the Korky part). The two parts look very close, but if you take out the red membranes and place them on a flat surface, you will see that they are not exactly the same in membrane height, which I think explains the difference in tightness. Save yourself the headache and buy this part, not the Corky version.