[R.C.]

Originally Posted by Michael Hill

I'm guessing the roller ends have the 5/16"-18 thread in the ends to accept a 3/8" shoulder bolt, which will then ride in an FR6 bearing. Plug with the protruding hex shaft will take a hex pulley or sprocket to drive the roller and the plain roller plug will be the non-driven side of the roller and just accept another shoulder bolt.

EDIT: Picture of 254's robot from this year shows how (I think) it's supposed to work. https://www.team254.com/photos/72157...0/26920320025/

Nailed it!