These are well designed racks that tightly hold the bottles. The bottles kind of snap in and make for great travel racks. You can fill up a rack and toss it in your bag and it will stay together. This structure doesn't work as well for stacked desktop use, as it is possible to pull out a single bottle from the exposed bottom of the bottle. All racks have to be accessible from the top (i.e. birds eye) to pull bottles out.