Middle 4 way used on 120 degree angle tents, in the inside bays.  Works for top of wall and peak both.

  If the peak and top of the wall angles are the same on your tent, then they should both be 120 degrees.  For a set, you would need at least 6 of the 3 ways, then could add these 4 ways to make it as long as you need.  Generally, strength is not the reason to add more brackets as they are wicked strong!  More brackets are used in order to have smaller straight pieces to carry around.  Most people like to use 5ft maximum horizontals for easy transport, so a 15ft long tent would have 3 bays, or 6 of the 3 ways, and 6 of the 4 ways.