I have to start leaving a key out for a friend to get in my house. I don't want to go the hidden rock method. I liked this idea. The fact that you need a code to gain access to the key. Any other ideas? I saw a version where the key was hidden in a thermometer, but I'm looking for a little more security. Like I said, I liked the above 'key combination access' style. Anyone use something similar? Where is the best place to get one?