The two “sides” are  meant to be used with either “center” piece (If you have the North Nova Pro with ShiftLock you will know how it will be used.

Cut to use with off the shelf ¼ X 1.5 inch bolt and nut (stainless suggested) the nut space isn't made to “Snap” the nut in, I used a dab of silicone to hold the nut after the fact (Just lazy)

The rounded top mount is for a ½ inch pole, and has a slot to thread through a velcro strap.