Flexible Impeller Pumps use spinning food grade neoprene impellers to create a pressured output. The food grade neoprene material allows it to be flexible and force the liquids out. This unique design means that the impeller will eventually wear down. A well-maintained impeller is key to a functioning Flexible Impeller Pump. Impellers last up to 3 years before they require replacing (it depends on the application and the amount of use).