Not as stiff as the C-Frame or X-Frame, but a good chassis made from glass-filled nylon for comfort and a Carbon Injected knee for that rigidity which reduces the ACL, Meniscus, and MCL injury risk. The Z-Frame is also CE certified as a medical device and as impact protection. Next step up is the X-Frame for a stiffer chassis and the top line cage-type brace or the C-Frame Pro Carbon knee brace, if you are looking for a single sided hinge. • Injected Composite chassis • Slim hinges for superior bike feel • Aluminum hinge covers for rigidity and endurance • Reduction of forces to limit knee injuries: • ACL, Meniscus and MCL • Certified as medical device: • EU CA014741 • USA FDA 10048761 • CE tested and certified as impact protection: • Knee EN1621-1 • Hyper extension limitations 5º, 10º, 15º and 20º for ACL injury reduction • Low-profile shin bone pad for excellent boot fit • Comfortable, easy-fitting and low-profile strap system • Customized fit with interchangeable hinge padding sizes • Size: S-XXL • NEW SIZE XXL