If you're going to bring your keys during a run, it's best to stash them in a closed-up pocket compartment, like a buttoned-up pocket on your shorts or a zippered pouch on a storage belt. That's just the best way to save yourself the hassle of losing your car or house keys. If you'd rather not have keys jangling in your body while pounding the trail, RunLock offers an alternative solution.
Instead of keeping the keys with you, simply hide them inside the RunLock and hang it someplace you will come back to later, like your SUV's rear hitch, your car's roof rack, or a secure beam right outside your house (if you didn't bring a car along). This way, you can do your five miles (or, let's be honest, one mile) without having to worry about losing your keys somewhere along the way.
Measuring about twice the size of a conventional padlock, the RunLock is huge. The main reason for that is the spacious compartment where you can hide your keys, which measures 2.7 x 1.6 x 1.2 inches, allowing it to accomodate even the largest automobile keys. Opening both the shackle and the compartment requires entering the four-digit combination (10,000 possible combos), which can be set and reset as many times as you want (provided you know the previous combination, of course -- if not, well, tough luck).
Is this secure? Looks like it. While the stainless steel shackle looks thin, it actually isn't -- the padlock is just so huge that the shackle looks disproportionately slim. It features weather-resistant construction, stainless steel body, and rubber sides for scratch protection.
The RunLock is available directly from their website, priced at $44.99.