I have the lang V9 boots which i bought after a knee injury. I like them alot. There not a real performance boots but i wanted all the knee protection i could get. I have set them off, meaning the boot retracted back in a few falls and they snap right back into place. I cant say they did anything for sure. Iam not even sure there still selling them anymore as they are very expensive boots.But if your after the best knee protection i would getem if you dont mind spending a little more for boots. I think i paid about $525 for mine which i got when they first came out. Before that i had atomic race boots.