Riser bolt diameter

[Troll]

I have a set of H-D 4 1/2" pullbacks, and they have an adapter bolt in them that screws into the riser as 1/2 13 and allows the 12x1.25 nuts that come with the normal bar risers...

[Brent Duncan]

anyone know what the stock riser bolt diamerer is are they a 12mm bolt?
looking at aftermarket risers and dont watnt to do any modding to the tree or buy adapers if possable. i know the Phat II risers are nice but im looking at others as well.