KRÜSS calibration standards are used to ensure maximum measurement accuracy over a long period of time. All measurement devices should be calibrated and adjusted regularly. Many of our calibration standards for digital refractometers are traceable to an internationally accepted standard according to N.I.S.T. For polarimeters, we offer a selection of PTB-certified premium quartz control plates and more cost-effective quartz control plates with a factory certificate traceable to the PTB. Our density standards are very inert and guarantee a long shelf life of 5 years unopened. We also offer high-quality, certified standards as control and reference solutions for melting point determination and for our flame photometers.