Okay so I just realized that this thing came with instructions!!

But I'm still confused.

"GRAFLEX ROLL FILM HOLDER INSTRUCTIONS

The roll film holders can be attacked to Graflex or Graflok backs. To fit to the Graflok back, a Graphic Roll Holder is required..."

What is a Graphic Roll Holder? Isn't that what I'm trying to attach? One needs a Graphic Roll Holder to fit a Graphic Roll Holder? Wha!?