It is a plastic and magnetic spare part in a pump. This part is found inside the pump, which is used to drive the water out the pump, and their warranty is limited as they get worn out like a Tyre of a car. Application Impellers are used on specific pumps and models. It is advised that you use the exact size impeller for a specified pump model. Note: impellers need to be cleaned now and then to increase their life span, as they can get worn out and the dirt can cause the pump to get clogged. This is the WH5000 for the new model design. Therefore this part will only fit your pump if you have the new design of the WH5000/10 pump. If you are unsure of which model you have, please send us a picture of your pump to shop@waterhouse.co.za and we will match the correct impeller for you.