As part of the Altra All-Weather Series (AWS) the RSM (rain, snow, mud) Lone Peak 4 Mid is made to face the elements. It features a brand new eVent upper, a crazy breathable, 100% waterproof material. With billions of tiny pores in the material means it breathes in any condition, wet or dry, while still letting sweat escape. This fabric is the leader in breathable, waterproof technology available on the market. The upper takes on a new look with an updated mountain design, while the updated outsole features multi-directional lugs.