It would fall under "more elite".
In order for the coolant to jet properly, we have to avoid the effect by which the coolant is sucked out of the sides.
So it's a little calculation exercise. Now you'd think that it would simply involve making sure that the jet ID cross section is smaller than the outlet's cross section, but you actually have to calculate the hydraulic equivalent of the "ring" cross section.
In this link:
http://www.lmnoeng.com/PipeDuct.htm
you can see a formulae to calculate the hydraulic equivalent for both a square tube, and a ring-shaped tube.
[ed: sp]