[A] FRONT SECTION - TIP OF THE SHOE
A reinforced front section provides better protection of the toes against knocks. It is important that the tread continue to the very tip of the shoe to ensure the necessary traction during the last part of the thrust provided by the toes. This phase of movement is particularly crucial during steep climbs in unstable terrain. The tread arrangement shifts progressively with increasingly small and more tightly spaced lugs leading up to the toe bumper.

[B] METATARSUS SECTION - CONTACT ZONE
This is the most important part of a sole for mountain trail running. It must provide a number of complex, often contradictory, functional solutions, such as puncture withstand against rocks to avoid any pain in this very sensitive part of the foot and flexibility, a fundamental feature particularly when going uphill to avoid wasting any energy. These two characteristics must be accompanied by good cushioning, provided by special materials and inserts. Maximum comfort is required for the metatarsus during fast, steep descents. In addition, the sole and the upper of the shoe must function perfectly together in the metatarsus section to ensure good stability, notably in uneven terrain, and effective propulsion under all environmental and weather conditions.

[C] ARCH SECTION - ARCH
In some cases, this section remains fully in contact with the ground to enhance the roll of the foot, however it can also be raised to improve braking during descents on unstable, humid or grassy terrain.
More rigid inserts and a bracing "high-wall" design in this section reinforce the support of the arch. That is a clear advantage in rough terrain when it is difficult for the sole to remain in contact with the ground. This is a fundamental characteristic for long-distance running to avoid overloading the arch.

[D] HEEL SECTION - HEEL
During mountain races, particularly during descents in hard, rocky terrain, the impacts on the heels can represent three times the runner's weight. It is essential to provide better cushioning than that found in most standard running shoes, even if that means adding a few grams of additional weight.
Vibram® has developed a cushioning system in the heel section that improves both compression and the distribution of forces from the heel to the toe. The result is lower deceleration values, slower transfer of forces through the ankle and, consequently, much lower impact during descents on very steep slopes. The overall result is a much higher degree of comfort over long distances.