We need to change the anode for the Featherstream propeller at least every other year. Darglow engineering which is the company that made the prop is also the only manufacturer of anondes, Darglow is a really good company and i did get really good help from them when i bought the propeller. The anodes are custom made to fit the propeller:
These are really expensive ones about 50 Eur each with shipping cost from UK to Sweden. I found other anodes at a local hardware store that with a little tuning will fit perfectly, cost per anode about 11 Eur.