This is a quality base for a large umbrella.  I especially like the way it can be easily drained of water (ballast) for storage in the off season.  We have been asked if the water ballast is sufficient for the 11" square umbrella it is holding.  I, too, had that concern when I ordered it. To address that, I purchased 40 lb. sand bags for the purpose of laying on top of the base for additional ballast (the base is out of sight, behind a patio couch).  I am happy to report that we have not needed to take that additional step, as the water ballast appears to be more than sufficient.