Refractive Index or Abbe number (?d or ?e) can be measured at different wavelengths ranging from 450 to 1100nm. The DR-M2 digitally displays measurement result of refractive index or Abbe number on the LCD. Measurement can be achieved by matching the boundary line with the intersection point of the cross hairs. This refractometer is connectable with Digital printer DP-22 (B). Reflective Index Range at Wavelength 450nm: 1.5219 to 1.9220nD. Reflective Index Range at Wavelength 589nm: 1.4700 to 1.8700nD. Reflective Index Range at Wavelength 680nm: 1.4545 to 1.8544nD. Reflective Index Range at Wavelength 1100nm: 1.2743 to 1.6840nD. Minimum Indication: Refractive Index 0.0001 - Abbe number: 0.1. Measurement Accuracy at Wavelength 589nm: +/-0.0002nD. Per each. Atago #: 1414.