|Piston Ring Base Materials
RM5 is a flake graphite cast iron specifically developed as a 2-stroke engines' piston rings base material because of its morphology and its matrix' constituents.
Formerly used on all the piston ring grooves, nowadays, with different coatings and shapes, RM5 is the standard base material for all piston rings, except for the first groove made by Darcast.
For modern high performance applications, Daros has developed the Darcast™ compacted graphite iron (CGI), which offers high strength combined with minimum wear.
It is nowadays used only on the first groove piston ring, as that's the most stressed ring due to its position close to the combustion chamber.