While we doubt you'll ever use it for actual rope duties during mountaineering adventures, the Keybrid Carabiner Key does add some amusing novelty to your erstwhile boring pocket clutter. I mean, it's a real key with a little carabiner thingie on its head.
What will you do with a carabiner of that itsy-bitsy size? Well, you can use it as a key fob that also happens to be a key. Or just use it as a regular key that's a whole lot easier to get onto a keyring, saving you from the hassle of having to try to peel at thin wires, breaking a couple of fingernails in the process.
The Keybrid Carabiner Key is an erstwhile regular, working key blank that you can take down to the local locksmith for carving into a fit for any standard lock. Instead of just a small hole on the head, though, it comes with a large one that's closed off by a pivoting latch similar to the one on a carabiner. That makes it a heck of a lot simpler to hook onto stuff, so you can detach and reattach your key to anything without much trouble.
Want to keep a key on your belt loop, along with your carabiner mug? This should do the trick. Same with your backpack loop or your bracelet or wherever else you fancy. The Keybrid Carabiner Key will be available in the Fall, although price is uncertain (expect it at around the $9 range, though).