Eye Shield Anchors M6 x 80mm - what sized drill bit

[Spare tyre]

got a packet of these sitting about that i'd like to use for something

http://www.screwfix.com/p/eye-shield-anchor-m6-pac...

what sized drill bit do i use, says M6 on the shaft

sorry for such a simple question

[Spare tyre]

thanks guys, no it doesnt say on the outside, usually it does!

Just says M6 which is the bolt i guess

[Spare tyre]

perfect - was away from my tools so was just trying to check before i got home incase i needed to grab any extra bits

it was 12mm

thanks