Descriptions: Powder buffer solution provide long shelf life and stability and are ideal for low volume use. Each pack makes 250mL of buffer solution. It provides indefinite or long shelf life and stability, ideal for low volume use. It's lightweight, inexpensive and takes up very little space. These buffers are accurate to within ±0.01pH units @ 25°C and remain stable over long periods of time. Put into solution only what you need, when you need it. Features: 4 packs of popular pH buffer solutions, 2 packs pH4.01 and 2 packs pH6.86 Simple to use. Just add 250ml per powder packet Powder has an indefinite shelf life Easy 3-step procedure is written at the back of the packet Specifications: Each Pack Volume: 250 ml. Each powder packet/sachet makes 250ml of solution (when mixed with distilled or deionized water) Accuracy: ±0.01pH at 25°C Size: 7.5x6.5cm/2.95x2.56" Quantity: 3 Pcs/1 Set Note: 1.Transition: 1cm=10mm=0.39inch 2.Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid. 3.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! No Retail Package Package Contents: 2 x pH4.01 Calibration Powder 2 x pH6.86 Calibration Powder