Negative Potential Ceramic Ball 1.sizes: 2~3,4~5,6~8mm or etc 2.used for reducing ... to 0 mv ~-500mv, PH value to about 7.5, and many air bubbles produced oxygen-rich water.Negative ... mv ~ - 500mv, adjusted PH value to about 7.5, and many air bubbles produced oxygen-rich water when this ... ,which is a useful element to the body health;3) With the high solubility and strong penetration,negative potential ...