Hmmm..... Hidden gas block.... Sneaky sneaky
That is the way I understand it. Bushmaster invented the Dissipator and that is the way they did it so anyone else using mid length or rifle length gas system on a carbine length barrel and calling it a dissipator are selling some sort of immitation that isn't what the original intention of the dissipator was.
Think about what the word dissipation means. It's about heat being dissipated and has nothing to do with gas system at all.