Bests & Worsts Reviews from Amazon

I stacked 3 units. They fasten together with screw-in connector pins and are very stable, no tilt or wobble. Directions indicate you could stack up to 4 units. I'm using them to store yarn in clear plastic salad containers in my crafting room (see my photo). They look very elegant. The size is perfect - much better than standard shelving. Note that the interior height between the shelves is 5 3/4" for the middle shelves, but only 5 1/2" for the shelf space where units are joined.