bones, are you getting one custom made? Depending on the string maker, you may need some more information on how you want the serving (especially length of serving as it goes over the cams). That's the real nice part from getting it done from a string maker. If they need that info, run a piece of serving or thick thread right along the string that is on the bow. Mark it where you want the serving to be put and then measure it. Your string maker should also want to know what types of nocks you use in order to get the correct size middle serving on.

You will also need to know the type of material to use. There are pluses and minuses to every type out there, so I would talk to the string maker about it. In my area, there seems to be a lot of small shops making their own strings.