Like others responding to this thread, I tried to "open" the joiners, but gave up the task for fear of breaking the joiners. I installed three 9-foot (6+3) GS shelves along a brick wall of my train room. The brick mortar joints in rows provided the correct vertical spacing. The slightly irregular surface of the bricks created a bit of a "jog" where two shelf pieces fit together, but IMHO it's a minor flaw.
Mike Mottler LCCA 12394
