You have 2 receiver options for either version of the tailgater, 211K or 211z. Either one supports connecting the trailers onboard antennae to enable local digital channels to appear integrated into the Dish onair guide.
The older 211K is a slightly larger receiver and the local channel coax passthru is builtin. You can find like new 211K at some dish dealers and many times on Craigs list or ebay. If you buy a used 211K it must have been disabled with Dish by the previous owner or dish will not add it to your account. Best to buy from a local dish dealer, they can still sell new and refurb 211K.
If you get the newer 211z by buying by itself or in a tailgater bundle, you will need to spend another $49 for the local channel adapter. It plugs into one of the 2 USB ports and provides the local channel coax passthru.
Lastly, I have the 211z and local adapter plugged into USB port1 and an external harddrive plugged into USB port2 for DVR function. I find this combo does not work well for DVRing local channel shows. I believe its because of memory bus contention caused by USB port 1 and 2 sharing the same data path. I plan to change to 211K and resell the 'Z' gear. For now I only DVR satellite shows.