Has anyone used one of those magnetic key holder cases for storing a back-up key on the vehicle - usually under a fender? Thanks, Kip
Those have been around an long time - decades. I wouldn't be surprised that would be the first place any would-be thief would check, just on the off-chance to get lucky. I also wouldn't trust the strength of the magnet, considering the roads or that anything else could happen - run over a rock or a branch, anything could potentially knock it out of a wheelwell. If you have any later-model key, they're pretty expensive to replace, too.
Ditto on not using them as most the cases are not water proof and will ruin your key if it has any electronics on it.