Shelves branch off a central spine in alternating directions, which is where the tree comparison comes from and why nine tiers fit into a 15 x 10 in footprint. Large shelves measure 12 x 8 in and small ones 6 x 8 in, spaced 5.5 in apart - sized for paperbacks and hardcovers stood upright rather than stacked. The top shelf takes 44 lbs and each other shelf 22 lbs, 132 lbs overall. At 42 in tall and 20 lbs it suits a desk corner or a narrow alcove. A user manual is included.