Electrical measuring instruments and standards and parts thereof, namely, resistance bridges and current range extenders for measuring resistance, temperature bridges, teraohmmeters, precision current transformers, impedance measurement systems comprised of phase sensitive detectors, current comparators, and AC bridges; high voltage capacitance bridges, thermometers, AC-DC transfer standards, transconduct amplifiers, watt meters, volt meters, potentiometers, ohmmeters, inductive dividers for calibrating resistance or voltage ratios; resistance standards for use as reference standards with resistance bridges, temperature bridges, and digital multi-meters or for verifying the performance of the aforementioned equipment; temperature stabilized standards with their own built-in temperature controller used as reference standards and artifacts to verify measurement performance of precision metrology lab equipment, namely, resistance bridges, temperature bridges, thermometers, and digital multi-meters; air standards used as reference standards and artifacts to verify measurement performance of precision metrology lab equipment, namely, resistance bridges, temperature bridges, thermometers, and digital multi-meters; oil standards used in oil temperature baths as reference standards and artifacts to verify measurement performance of precision metrology lab equipment, namely, resistance bridges, temperature bridges, thermometers, and digital multi-meters; current shunts, voltage standards; oceanography instruments, namely, salinometers and constant temperature baths for fluid and air

calibration