Hydrion Buffer Capsules are perfect for quick and easy pH meter calibration. When mixed with distilled or de-ionized water, a Hydrion Buffer Capsule will accurately produce 100 ml.of solution at pH 2.00. Hydrion Buffers are free flowing soluble powders that prepare clear or color safe solutions in minutes. A built-in preservative ensures long-lasting solutions in in color-keyed in in to easily identify the ph value of the buffer solution.