Product review (5 stars): Could be your cheap dishwasher fix
After 10+ years, my dishwasher started having issues draining completely at the end of the wash cycle. In dismantling and cleaning all the involved parts (thanks, YouTube instructional videos!), I saw that these flapper valves were both corroded, probably from our very hard water and also detergent residue.

NOTE: My GE Profile model uses two of these flappers: one in the drain pump assembly and another in the drain hose. Although these flappers are supposed to be the same, I was not able to fit this brand-new one into the drainage hose (it was slightly too large). When I tried to wedge it in anyway, the flapper didn't work properly. So, compare your old flappers to this new one before you toss them out!