We learned a lot from developing our C-Frame and X-Frame knee braces, and we recognize the need for a great knee brace that wont break the bank. 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. The Z-Frame is also CE certified as a medical device and as impact protection, maybe its time to get rid of your knee protectors and get yourself a knee brace?