Roll Firm : when race conditions are rough or slick
Roll X-Firm: when race conditions are hard, smooth and dry
Roll XX-Firm : when race conditions are perfect hard, smooth and fast.
MPC Black Magic Firm
Durability
Best for a Sprint
Best Grip
In tight Corners
Hardness
83A/60A (Soft)
Wheels Rebound
Highest Snap Back
Roll
Consistent Fast
Application
Road Circuit
MPC Black Magic XFirm
Good for Marathon
In All Conditions
85A / 60A Medium
Highest Stability
Allround outdoor
MPC Black Magic XXFirm
Highest durability
On Smooth Asphalt
87A/60A (Hard)
High Stability
straight line speed
Road Marathon and Allround outdoor