Have you ever wondered why the riveted metal tab that holds the end hook on a tape measure has slop in it? It's not because it was manufactured by a shoddy company. Gareth Branwyn at Make explains the reason:
If you'll notice, the inch marks on the tape actually start 1/16″ short. That's because the thickness of the hook itself is 1/16″. So, if you take an inside measurement (pressing the hook end against the work piece you're measuring), you will get an accurate measurement. But also, if you hook the end onto a work piece, the play in the rivets will move the hook out to compensate for hooking onto the material, creating a 1/16″ gap between the hook and the tape, allowing for an accurate measurement.
This is just one of five wonderful things about tape measures you may not know. If you already knew all five things, please crow about it in the comments and remark how surprised you are that not everyone is aware of this information.