i use them outdoors. i went to the windy desert for a few months and over that time, the locking mechanism became more and more stubborn and the key was being very difficult to move. lubricant did not resolve the issue. it has been a few months since i have left the desert and the lock+key have been gradually working better and better. i love that there is multiple keys. i have been using these locks for over ten years now. i usually lose about one a year and hang onto about 3 at a time. i paint the keys and locks to differentiate them from each other. i tuck the lock between my belt and pants when riding my bike and it makes my pants fit perfect. i leave my bike locked outside stores in the city and have bikes locked up in my backyard, and keep a lock and cable attached to my truck, sometimes with a bike attached. as far as i know, no one has been attempted to steal my bike. warning: i was able to figure out how to defeat these locks.