triple-square fastener size

[Douglas Frank]

Haudi all,

After a helpful hint from a lister, it appears that I the fuel filter is
fastened under my A4q with a triple-square bolt (sort of like a 12-pt. Torx).

Tonight I'm going to stick a wad of bubble gum in there to get an impression
of the tool needed to get it out.

My question to the list is, how do I measure the impression?  These things
appear to come in even metric sizes (6, 8 mm etc).  Now is that the outside
diameter of the bit, or what?

http://www.bobstools.net/Store/LS60750.html

thanx!
--
Douglas Frank Compaq Computer Corp.
ZKO           110 Spit Brook Rd.       The older I get,
603-884-0501  Nashua, NH USA 03062       the better I was.