Flex 8 – (1 Soft - 10 Stiff) Articulating Upper Cuff – Featured on the pro models, an articulating cuff allows maximum range of motion. The upper flexes independently like a hinge without material buckling. Rear Asymmetrical Flexzones – Welded PU and Lycra create a unique flexzone that helps promote an incredible amount of motion. Fit Built in TPU Shoe Horn Women's Slim Fit Semi-Rigid Quarter Panels – A more form fitting quarter panel hugs your foot and allows more responsive movements. PU Tongue Compression Panel – PU Panels displace the lace tension across the foot, eliminating pressure points on the riders foot. Liner & Lacing Reflex Liner – The Reflex features totally new tongue design that wraps your ankle for a better fit and more supportive flex. The new Reflex liner tongue has tapered edges reducing material overlap inside the binding. This feature reduces bulk and eliminates air gaps for a snug, full contact fit. The notched top cuff improves your range of motion and has a better fit for larger calf muscles. The Reflex also has a 3D molded Impact EVA bottom featuring 2.5 degrees of cant, toe lift, a deep heel cup and a supportive arch underneath your foot. Dual Lace Zones with Lace End Keeper – All men's and women's adult bindings feature LF's dual lacing. The dual lace zone system allows the lace tension to be different in the lower and upper zones. This gives the rider a custom fit for a secure and comfortable feeling. EZ Glide Lace System – Specially designed injection molded parts that allow the laces to move unrestricted when tightening and loosening the binding lace zones. Trek Liner Bottom – Reflex liner is given an EVA bottom with flex grooves for comfortable walking and solid traction on all types of terrain. Adjustable Length Upper Velcro Strap Baseplate 4D Chassis – The 4D Chassis has the smallest footprint in the industry! The small footprint allows the board to perform at its truest flex, giving you maximum response. The 4D construction also reduced the weight by 15%. This means a more responsive binding, softer landings and a more comfortable ride. NOTE: 4D Bindings are only compatible with Liquid Force Flextrack boards.