I Bought THREE. These Are THE BEST.... SOLID WOOD, This Series Comes in several Variations (Shelf Wise) I Opted for the Three Shelf Unit, Ordering THREE of them, Shelves DO NOT SLOAP IN THE CENTER (Like Particle Board Does) This is SOLID. Each Shelf and Surrounding sides & top & Bottom are apps. 3/4" in thickness. I Plan to order 3 MORE TODAY.  I have mine all stacked on top of each other, with 2 small, hinge (like on a door) on each side ALL are secure with the "Hinge's, As I Purchased 3 Units, stacking was easy and held together with 8 small Hinges. (One Screw in the Unit at top and bottom Unit, 2 Hinges on each Unit Left / Right Side) to hold Units together tightly, I'm Sure there are several options if, you are ordering several Units to hold together IF, Stacked One on Another (GREAT LOOKING IF STACKED)