Sammons Preston D3 fabric is a revolutionary fabric, the next dimension beyond foam and neoprene. Used for maximum breathability, insulation, compression, durability and recovery. D3 Knee Pull-On Hinged Knee has reinforced patella with adjustable buttress. Open patella and open popliteal. Hinged stays with hyperextension stop at 170 . Loop lock stabilizing straps. Leather hinge pockets. Latex free.