I wanted to stick a QR-Code with a link to my website on my car, so people could scan it while I was out and about. I didn't want a message, just the QR-Code by itself. The regular square stickers sold by Zazzle weren't meant for outdoor use so I looked at the bumper stickers instead.
This one is perfect; with a little cutting out by hand, I got 4 stickers! Now I just need to convince my family to "wear" the extras on their cars too! :)