The Mammut Ducan High GTX sneakers with high ankle support literally give us a spring.. Vibram Flextron outsole features a spring steel outsole that absorbs shock transfers energy and maintains a natural stride on the trail and also provides reliable grip on different surfaces. This provides a solid foundation for our treks and the waterproof, breathable GORE-TEX membrane allows us to travel in any weather without worrying about it that our feet will get wet. This is a classic style in the Mammut family of hiking shoes.