Akadama 20 liiter bag small grain from Tochigi Prefecture. The size is 2mm to 7mm. Our akadama has many small bubble each ball, the bubble include air, root want to have air. The bubble also make easy dry. And ball surface is very rough. The rough makes root stimulation. That is the reason the root bite the akadama or sting this akadama. It is good for plants health.