I've got at least 600 miles on these and they're holding up great. As far as the zipper sliding down i haven't had that problem. When you flip the lever down it locks the zipper closed. Nice YKK zipper. I was worried about the size because I wear a 14B hiking boot. I wear a Dunham Cloud. They just fit. I don't have to stretch the crap out of them to get them on. One thing i really like is that you can take them off and put them on without taking off your shoes unlike a certain other brand out there. Also I wear a taller sock so the gaiters never rub on my skin. If these ever wear out I'll buy another pair.