Slap Ruler!

Remember slap bracelets? Aaron tang has come up with this, a metal rule that doubles as a wrist band, ideal for engineers or designers. I have a couple of niggles with this design, from what I remember of the slap bracelets they were made out of a curved piece of metal but I can't remember what they look like when rolled up, if these really work and were available to buy I would definately buy one!