Genuine Gerber 99-647 Flapper Used in several Toilet Models. It has the extra hole on the underside and includes the green baffle. The flapper Measures about 3 and 1/8 inches across. Other variances of the part number are G0099647, 99647, 0099647, 99-647 UPC: 671052602520.Genuine Gerber 99-647 Flapper is the replacement for 99-779. This Flapper Has The Word RUNNER Between The Hinges . It also Has A White Insert In The Bottom, And Is 2" Wide. Other variances of the part number are G0099779, 99779, 0099779, 99-779.