Dont feel too stupid.

All the bolt dumbos work for Zenith. The info on the pack is just a guide, its a lie to sucker the coin out of your pocket.

Bought some 3/16 washers. They have to be bigger than 5mm ID. Liars.
Got some 5/16unc nuts here, 13mm too small, 14mm too big. WTF, a 5/16 nut is meant to be 1/2 AF. 1/4 WW WTF its 2011 why you still making that?.
Got some 3/16 pop rivets. Steel ones are all good, alloy ones wont go through a 3/16 hole witout a lot of shoving and wiggling.