MMO is a coating consisting of a mix of rare earth metal oxides with either iridium or ruthenium as the active catalyst. Iridium is suitable for all CP environments while ruthenium-based anodes are suitable only for seawater applications. The exact coating mixture can vary from manufacturer to manufacturer. The key is that the manufacturer has a proven recipe and that we can predictably calculate its performance characteristics. This includes anode life based on accelerated life testing programs. Manufacturers apply these MMO anode coatings to a Grade I or Grade II commercially pure titanium substrate. Some of the common MMO anode shapes include wire, rods, tubes, strips, ribbon mesh strips and sheets, plates and discs.