Hey Metric Heads, we Americans are not as familiar with your system as we probably ought to be. Or at least this American isn't.... :D
Here's my situation: I'm playing with the FunnyBone drawings and looking at common metric wrench sizes. Now, the ideal size progression on my tool is 6,8,10,12,14,16,18mm.
It is my understanding though that 13mm is a very important and common size. It also happens to be very close to our American 1/2" which is an extremely common size here so I can see the attraction. My question is, how critical is 13mm? The reason is, if I include it then it throws off the whole progression of sizes on the tool and they need to be 2mm apart to work out and be stepped correctly.
So I guess I'm wondering, what are the most important metric sizes that the rest of the world needs? I have other configurations worked out if the above mentioned list isn't good enough.