Among the many tools I've lost over the years, one of those Swiss Tech tools is numbered. It was not, alas, a reliable hanger-on to the key ring. Mine was one with tiny little screwdriver blades hinged into the larger blades, making it a really handy bladeless multi-tool for traveling. I've never seen another like it.
I also had a "utili-key," and that also opened up somewhere in the world, and disappeared. That was a nice one for traveling, because it hid on the car keys but had an actual, sort of knife blade, which probably was not TSA compliant, but snuck through.