The high-quality CPY20 buffers guarantee pH calibration to ultimate precision. They are produced and bottled in the permanent calibration laboratory that has successfully passed the tough DAkkS accreditation (German accreditation authority). The buffers are specified with an accuracy rating of +/-0.02 pH. They are traceable to NIST and PTB standard reference material and contain only FDA-listed preservatives. Using CPY20 you will achieve correct values that you can rely on.