Bolt sizes

hi all

this is probably going to sound a bit stupid but could someone tell me what does M6 mean when talking about bolts?

thanks alex

6mm diameter in size. Not the lenght, but the diameter. So if your using a M6 bolt, you need a 6mm hole for it to go in, or a 6mm Tapped hole etc.

Mr Stu

i have bolted down the m6 :)