Refractometer - Clinical Refractometer measures urine specific gravity, or gives the refractive index in seconds. Dimensions Place a drop or two of a sample on the prism and read the results. Sper Scientific portable refractometers work in ambient light with no battery or other power source necessary. A refractometer measures the extent to which light is bent (refracted) through a liquid sample. They are commonly used to help identify or confirm the identity of a sample, assess the purity of a sample, or determine the concentration of a solute in a solution. They can be used in labs, on production lines, in the field or anywhere. Simply place a drop or two of a sample on the prism and read the results immediately. With reasonable care, their reliability, precision, and optical performance will last forever. All Sper Scientific refractometers come complete with: • Rubber coated hand grip and construction, which insulate the test solution from inaccuracies caused by the user's body heat. • Covered eye piece and bright, clearly defined scale, with large easy-to-read measurements. • All the accessories for immediate use, including calibration tools and solutions, full instructions, transfer pipettes and protective cases. 6½" × 1½" (165 × 38 mm) Weight: 3.0 oz. (86 g).