The SPER Clinical Refractometer works in ambient light without batteries or other power sources. It can be used in labs, in the field, or anywhere. Place a drop or two of a sample on the prism and have results immediately. The refractometer measures protein concentration, urine specific gravity, or gives the refractive index in seconds using a few drops of blood serum, plasma, urine, or albumen. Serum Albumen range is 1-12g/dl, resolution is 0.2g/dl, and has an accuracy of ±0.2g/dl. Urine Specific Gravity range is 1.000 to 1.050, resolution is 0.002, and has an accuracy of ±0.002. Refractive Index (nD) range is 1.3330 to 1.3600, resolution is 0.0005, and an accuracy of ±0.0005. A rubber-covered hand grip helps insulate the test solution from the user’s body heat. This refractometer includes a sturdy carrying case, calibration solution, pipettes, and a screwdriver.