Lasco 3-1/16" O.D.x2-7/8" I.D.x3/8" Thick Rubber Flush Valve Shank Washer. It is a universal fit. Beveled shape rubber flush valve shank washer. Used to seal inside of tank. Fits 2 inch flush valve. 2-7/8 inch inner diameterx3-1/8 inch outer diameter Fits most.