2 major problems, both material
This plastic is both brittle and binds to itself.  First the binding: I had to literally break apart multiple of these when they screwed together and would not come undone.  I coated all my threads with a lithium grease crayon and fixed that, but now my pills have a stale petroleum essence to them.<br /><br />The other problem: they are brittle.  You can't even drop a single empty container, its threaded edge can shatter under its own weight.  Don't stuff a long stack into your luggage or it's likely to snap in the middle and ruin one of your containers.<br /><br />Over the last 2 years I've lost about half of these to breakage, with cracks and chips in many of the remaining.
Rating: 2 stars