Reichert Technologies refractometers are accurate to 0.0001 refractive index
The AR9 refractometer is accurate to 0.0001 RI and 0.05% Brix.
The AR9 refractometer has measurement accuracies of 0.00002 refractive index (RI) and 0.02% Brix, and controls temperature at the sample interface to 0.03°C. The refractometer is accurate to 0.0001 RI and 0.05% Brix. Both include Peltier temperature control through a touchscreen that also allows the devices to connect to other instruments.