Obviously the terminal is JL's XB-BTU, but I couldn't find any documentation regarding what was included with the part if any. I visited a local JL Signature dealer today and they didn't know what the ring post in the picture was. They opened the XB-BTU package and there was the post.
All three outputs accept from 1/0 to 8 awg wire via included adapter rings and two allen wrenches are also included.