I bought some Salomon shoes about 3 years back with a quick lace system, the man in the shop said the material was kevlar, which is really strong, they make archery strings with the stuff and bullet proof vests etc, Mine have been worn to death, no breakage, but now I find the toggle bit seems to work itself a bit slack, but as the soles are now flat as a pancake and no grip whatsoever, I think they have done the job perfectly.