If I remember correctly you can connect a GK head to a GK cab using a 4 pole neutrik connector that will sent extra power to the tweeter (or something like that). For my current non-gk cabs I use a standard 2 pole connector. Maybe I will try a GK cab 112 out in the future. 
It was a cable, but it gave you a separate section of the amp with its own knobs specifically for the tweeter to further dial in tone. Looked cool!
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