HM Digital's pH buffer solution comes in powder form, so it's lightweight, takes up very little space, is inexpensive and has an indefinite shelf life. FEATURES Variety pack of pH buffer solution. Simple to use. Powder has an indefinite shelf life. SPECIFICATIONS Total volume: 1.2 liters. Each powder packet makes 100 ml of solution (when mixed with distilled or deionized water) Contents: 3 packets of 4.0 pH, 6 packets of 7.0 pH, 3 packets of 10.01 pH Extra: Includes one empty 100 ml bottle Accuracy: +/- 0.02 pH at 25 degrees Celsius Preparation directions included with the pack