The upper materials are very durable with a minimal water pickup. The midsole is very flexible and keeps the weight down (sub 200 grams!). The height of the heel cup is slightly reduced in order to reduce pressure at the Achilles tendon. Terrain feel is remarkable thanks to the low profile of the sole. The shoe promotes the natural movement of the foot, itï's like running in a pair of socks, but socks that provide thermal and impact protection, and traction. The outsole is designed with a pattern that is optimized to grip on hard as well as on soft surface, with an aggressive pattern where dirt is steered away to the sides in diagonal channels (it's the same principal as in tractor tires). Acceleritas4 outsole is crowned with the jewel among "sticky rubbers": RB9X. This innovative rubber compound provides incredible traction on both wet and dry surfaces, without compromising the durability!