They come in two sizes. The taller ones are perfect, but the shorter ones work as well. My foam dice work better in the taller boxes because they need more room to rotate within the box. Hard plastic dice work well in the shorter ones.
They also hold up fairly well. I have been using them for three years now, and have not had much breakage. The lids are harder plastic and will sometimes crack. The lower portion is softer and the corners of the boxes occasionally squish in if the kids bang them too hard on the table.
If you are also frustrated by misuse and abuse of dice, I would highly recommend this method of managing them. It has cut-down on my dice-stress, and made my teaching life easier!