American Standard 7381002-400.0070A Dual Flush Valve - FaucetDepot.com
R&T A2422M 3" Dual Flush Valve with Push Button Dual Flush Toilet Repair Kit Toilet Tank Parts Replacement for 2-piece Toilet - Yahoo Shopping
Fluidmaster Dual flush valve 3-in Black Plastic Dual Flush Conversion Valve in the Residential Toilet Flush Valves & Repair Parts department at Lowes.com