Want that feeling of confidence from doing things right? Get our accurate, unbiased, independent and scientifically documented calibration standards and be sure your meter is working correctly. These buffer calibration solutions are suitable for the calibration of all pH meters. Each production lot is manufactured in our USA laboratory following carefully controlled written procedures and standardized against NIST standard reference materials (SRM) for highest accuracy. The finished product is assigned a unique Lot number and expiration date. These products will have greater than one year shelf life when received.