Any pH measurement is only as accurate as the buffer solution used for calibration. These buffer solutions are traceable to primary standards set by NIST.
Buffers 5001A40 through 5001A45 come with a quality assurance certificate per DKD and are particularly useful in quality assurance systems.
5001A48 through 5001A51 buffers are according to NBS and DIN 19266.
Mettler products are intended for sale/shipment within the US only. International customers should contact their local Mettler distributor to place orders for Mettler products.