Analog Refractometer Hand-Held Range 1.000 to 1.050 Automatic Temperature Compensation Yes Accuracy +/-0.0003 Resolution 0.2 Function Determines The Urine Specific Gravity Serum Protein or Refractive Index By Measuring The Degree of Which Light Bends As It Passes Through The Sample Features All Metal Housing Calibration Screw Clinical Scale Display Glass Prism Lanyard LED Illumination Non Roll Stand Rubber Eye Cup Rubber Grip Single Hinged Daylight Plate with Retention Plunger