EDITED:
When looking at CMSL, look at the air cleaner box, a small portion of the diagram has it shown on the right side of the diagram.
Several people have removed them and re-routed the hoses.
For lack of a better term, it is part of the emissions system, and connects just under the battery tray, above the swing arm. The breather from the cam cover goes here, and it vents out the bottom beside #3/4 exhaust pipes to the rear.
The other connection on the top of the emissions piece goes to the top of the air cleaner box, that biggest connector. The connector on the side goes to the cam cover. And of course the bottom is the drain tube routed beside #3-4 exhaust pipes to the rear.