Radial Pin is becoming very popular with cuemakers, both production and custom cue wise. Provides a really solid hit, never played with one, but people I know have them. Not sure the dimensions of the thread itself, but im sure if you google something like Billiards radial pin, you will come up with lots of hits.. mostly for cues..but it should still give you an idea of what it is
P.S Radial Pins are also available on Predator Shafts as one of their standard joints
P.S Radial Pins are also available on Predator Shafts as one of their standard joints