This breathable inlay was specially developed for the FENTO ORIGINAL and is the secret behind the ergonomics of this specific knee protector. As it happens, it ensures the correct distribution of pressure across the knee and lower leg, which prevents knee and back complaints. Once the inlay of your FENTO ORIGINAL has become worn after repeated use and no longer offers the right ergonomics, you need only replace this inlay rather than the whole knee protector. This makes the FENTO ORIGINAL much more sustainable.