Laminar Cover are made with high resistance carbon fibre (HS) 12k in combination with epoxy resin.
High performance carbon fiber can be High Modulus or High Resistance. High Modulus fiber provides a high stiffness whereas High Resistance, is more difficult to break.
With Laminar Cover, a solution of high resistance and not too stiff is searched, because the cover must be flexible enough to adapt to the rim shape, minimizing any possible gap. Therefore, in this case in convenient, to use a carbon fiber that can adapt to fit the rim but stiff enough to be stable during the movement. HM carbon fiber would be too stiff, less resistant and very difficult to assembly.
Epoxy is a thermoset resin. In the field of industrial resins, is the one with better mechanical performance and shows a very good aging resistance.