Descriptions: Buffer Powder Solution provides long shelf life and stability and is ideal for low volume use. Each package produces 250mL of buffer solution. It provides indefinite or long shelf life and stability, ideal for use in low volume. It is lightweight, inexpensive, and takes up very little space. These buffers are accurate ±to within 0.01ph of 25°c units and remain stable for long periods of time. Put only what you need in the solution when you need it. Features: 20 packs of popular pH buffer solutions, 10 packs of pH4.01 and 10 packs of pH6.86Simple to use. Just add 250ml per pack of powder The powder has an indefinite shelf lifeEasy 3 step by step procedure is written on the back of the packetSpecifications:Each pack volume: 250ml. Each pack of powder/sachet produces 250ml solution (when mixed with distilled or deionized water)Accuracy: ± 0.01 ph at 25°c Size: 7.5x6.5cm/2.95x2.56"Quantity: 3 pcs/1 setNote:1. Transition: 1cm=10mm=0.39 inch2. Please allow 1-3mm error due to manual measurement. Pls make sure you don't 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 Content:10 x pH4.0110 Calibration Powder x pH6.86 Calibration Powder