I was looking for the answer to Yak Traks which always get lost because they won't stay on the shoe.  These looked very promising but alas suffer the same fate as most shoe grips.  They might be OK walking on a slippery New York street but they're not suitable for serious mountain wear.  The grip is very good with these, and the rubber is much sturdier than Yak Traks but poor design gives them a thumbs down.  All they need to do is have a simple velcro strap going over the instep and they'd have a winner.  They were sized correctly and working on a pair of Sorels, but they slipped off several times during the first few weeks of use and now in under a month I've lost one for good.  Waste of money for mountain folks, probably fine for city slickers.