Quietest and most powerful fill valve on the market. Works with all toilets, including Kohler, Toto and American Standard. Maximize toilet performance and save water. 7 Year Warranty. High Efficiency Toilets HET 1.28 gal. Dual Flush, including DUO FLUSH. 1.6 gallon toilets with 2-Inch and 3-Inch flush valves (1994 and newer).Older high gallon toilets with 2-Inch flush valve (1994 and older). 2X greater refill rate than standard fill valves. Avoids excessive or inadequate bowl fill level. Quick, easy installation