MTL, or Merrell Test Lab, collaborates with top athletes. In so-called Skyrunning races, the running takes place at altitudes above 2000 meters, with an average incline of at least 6% uphill, and at least 5% of the route includes sections with a minimum of 30% incline. Due to the conditions, both the runners and the equipment must withstand rapid changes in weather, terrain, and terrain steepness. The Long Sky 2 Matryx is made to excel in these tough races! The tongue and footbed surface material of these shoes is made of "37.5®" material, which helps regulate temperature fluctuations. - Regular fit - The Matryx upper material is almost non-stretch, yet lightweight, breathable, and strongincorporating Kevlar fibers - The laces and 60% of the tongue material are made from recycled materials - ETPU footbeds provide a springy feel - The FloatPro midsole is lightweight and offers excellent shock absorption - The Vibram-made MegaGrip outsole provides good traction in both dry and wet c