Question about head bolt size

[bbb18c1]

I just finished watching the headgasket dvd and it says that the headbolts are 12pt. I only have 6pt sockets and checked at the local tool shop. They only sell the 12pt sockets individually. I was hoping to pick up a full metric set, but the sets only come as 6pt.

My question is what is the socket size I need for the headbolts? I am guessing either 12mm or 14mm. I bought both, but I would hate to have to run to the store during the teardown because I was wrong.

Thanks