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The State Standard certification scheme for magnetic induction measuring instruments in the 2-10-T range includes first class teslameters with an accuracy better than 0.01% [I]~ They serve for metrological certification of lower-class reference teslameters, superconducting magnetic induction standards, and magnetic measuring transducers in this range. It frequently occurs that the range of certified instruments has to be extended towards medium magnetic fields (below 2 T). The limited possibilities of metrological units as to use of superconducting solenoids, which serve as sources of strong uniform magnetic fields, make it necessary to carry out certifications in the less uniform magnetic fields produced by working superconducting devices. All these requirements are met by teslameters based on nuclear magnetic resonance (NMR) operating on the principle of nutation of the vector of total proton magnetization in circulating water.