Just pull it out of your shirt pocket and you have a 4" exterior Vernier caliper (0.1 mm metric and 1/16" inch scale) and a retractable ballpoint pen to mark down the measurements with. In addition, there is a metric screw thread scale and a tire tread depth scale.
So nicely made and so terrific looking, we simply couldn't resist it. So here it is for you to use and enjoy. Wow your friends. Made in Germany.