I live in a high-floor NYC co-op and need something that will be absolutely secure on a balcony railing. This planter can be adjusted both according to the railing width as well as providing clamps at its base, which also allow it to tightly grip the upright struts of the railing. It is the only one I found that offers this double security. I also found it easy to assemble, but while it has a water reservoir, it does not have drainage holes.