Note that there are two different packages:
Tow Technology package
Max Tow package
The Tow Technology has basic towing technology and should include the hitch, brake connector, and brake controller.
The Max Tow package increases the towing weight capacity and provides a second cooling loop for the battery (and perhaps motors). The increased cooling capacity is analogous to the transmission cooler in that it allows the truck to run continuously at a higher power output.