Our factory can produce high quality silica gel, yellow color change to white without cobalt. Size:1-3mm,2-5mm..4-6mm Our factory produced non-cobalt silica gel for many year to meet abroad demands.Our size range is: 1-3mm, 2-5mm, 3-5mm, 4-6mm..It's color can change from yellow to green or white after absorbing the moistures.