Based off the Multiboard Vertical Pole Mount. I have a shelf with poles running up on each corner, but they had a much wider diameter (~39mm) than the original worked for, plus I didn't want the sleeves for biting into the pole and preventing movement. Instead, I wanted this to act like a hinge so my Multiboard could as a cabinet door and swing open, so this version has a smooth surface inside the circle, so it can pivot around the pole.