Features of the Salomon Men's X Ultra 4 GTX Hiking Boot Trail-inspired agility: Drawing on our trail-running expertise, this shoe is lighter and more agile, so you stay nimble on uneven terrain. Enhanced stability: The new ADV-C Chassis targets articulations on the outer foot to optimize stability without limiting your mobility. All-terrain grip: The Contagrip MA Outsole grabs the terrain, even when it?s wet or slippery, giving you more control especially on descents. Drop: 11 mm Heel stack height: 31.5 mm Forefoot stack height: 20.5 mm Sizing advice: Choose the size larger than your usual Salomon size