It's time to get serious with your training and reach for new heights. The DS Sky Speed is a neutral, lightweight trainer that is ideal for tempo runs, intervals and daily training. The superb snug fit is ideal for fast running and the modified slip last minimizes weight, lowers the foot and increases road feel. The responsive ride is dialed in for midfoot strikers, yet heel strikers will also find a smooth ground transition. Add in great flexibility and you have now found your serious training partner in the DS Sky Speed.