and high quality. Light weight, easy to carry. Just add water or distilled water. For each powder pack,we can make 250ml solution. Use for PH tester measure calibration solution. PH Meter Buffer Solution Powder Set for Quick and Easy pH Calibration. Item Type:PH Buffer Powder Note: Please check as much as possible to make sure the item is what you need. Tips:The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use. Colour:As Shown Material:Plastic Package Contents: 100 x 4.00PH buffer powder 100 x 6.86PH buffer powder 100 x 9.18PH buffer powder Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.