Montrail Men's Fluidflex F.K.T. Trail Running Shoes FluidFoam Midsole - Offers soft cushioning and a responsive ride from heel to toe. FluidGuide Midsole Technology - Adapts to ever-changing terrain and provides the smoothest possible foot guidance and multidirectional stability. TrailShield Outsole - Lightweight, flexible material that is co-molded between outsole and midsole for underfoot protection from rocks, roots, and other trail debris. Gryptonite Outsole - In the high wear areas of the heel and toe area. Sticky carbon rubber with multi-directional lugs delivers aggressive traction across a variety of surface conditions. Seamless Upper Construction - Offers superb fit and a run free from irritation.