Vertical shelf support tube does not attach to your wall, it angle locks on the lower horizontal wall bar of the mount itself. The tube can be located on the bar anywhere between the wall brackets. There are two rubber bumpers on the lower end of the vertical support tube that protect your wall. The shelves slide into slots in the vertical support tube, with a coresponding 2 degree angle to level them under load. First component shelf distance is 18 1/2" below lower horizontal wall bar. Each additional is 5 1/2" lower. Dimensions are 1/8" x 14" x 18" wide, they are black anodized aluminum with polymer bead edging. Max. weight per shelf is 25 lbs.