American Standard 4385A.137 Yorkville 1.28 GPF Toilet Tank Only WhiteAmerican Standard 4385A. 137 Yorkville 1. 28 GPF Toilet Tank Only The revolutionary technology of the Yorkville VorMax toilet tank from American Standard has been independently tested and proven to clean 2 times better than conventional toilets. Dual injection flush valves deliver powerful jets of water into the bowl. Combined with the VorMax bowl featuring a CleanCurve Rim and EverClean surface, keeping the bathroom spotless has never been easier.