Review on High-Quality American Standard Tank to Bowl Coupling Kit - Model 7301021-0070A by Khiam Burton

The four neoprene gaskets in your US standard toilet tank (flap gasket, drain valve gasket and bolt gasket) WILL corrode after several years of tap water immersion. Although the actual failure of these seals will show up as a leak after many years, it is advisable to replace any of them if corrosion of any or all of these seals is evident. However, American Standard doesn't offer a "cistern gasket replacement kit" for their various models, and that sucks. Instead, the American standard requires the owner to purchase fully functional tank components to get the exact seal they need. This is a wasteful and costly policy. Two examples: 1) This is "US Standard 7301021-0070A Tank to Bowl Connection Kit". You must purchase bolts, nuts, and a tank seat gasket, none of which should NEVER be replaced, to get two bolt gaskets. 2) American standard requires purchase of entire flush valve assembly (www.amzn.com). /B003WWV8N6) - a large part that NEVER wears out - used to seal the damper and purge valve.