All Oakton pH buffer solutions are freshness dated, and standardized against nist-traceable References to ensure quality. ±0.01 pH at 25°c. Oakton pH buffer solution bottles are labeled with the name and CAS number for all ingredients (for "right-to-know" requirements), and are supplied with an MSDS. Oakton pouches are convenient, air-tight pouches with high-precision calibration standards. Ideal for field use- take them to your Test site for on-the-spot calibration. Each box contains twenty 20Ml pouches.