The Alpinestars Fluid Pro Knee Brace is lightweight, strong, and constructed from a high-performance glass fiber compound. The knee pivot system features a double pivoting hinge system incorporating tool-free, fast, easily exchangeable extension stops (0, 5, 10, 15, 20 degrees) to prevent hyper-extension injuries. The Fluid Pro incorporates a bio-organic engineering design for superb anatomical performance. Innovative patella/knee cup protection system is ergonomically sculptured and ventilated. Knee cup system is constructed from semi-rigid TPU backed by shock absorbing PU memory foam. Correct position of knee cup is secured accurately in place with top and bottom elastic straps, allowing multi-directional freedom of movement. Additional protection in strongly angled positions afforded by upper and lower patella cuffs.