Each hardness of the wheels has been designed to adapt to a type of surface based on smoothness or roughness.
In general:
- The softer the wheel (or the lower the “Shore” hardness number), the greater the grip and the slightly lower smoothness.
- The harder the wheel, (or the higher the “Shore” hardness number), the greater the smoothness and the slightly less grip.
The following table shows the type of surface suggested for each wheel hardness.
| FOX | PANTHER | MUSTANG | LEOPARD |
| Very slippery surfaces | Slippery surfaces | Medium surfaces | Adherent surfaces |
| Devil Match 36-39 | Devil Correspondence 42-45 | Devil Correspondence 47-49 | Correspondence Devil 53 - Giotto 57 |