Analog Refractometer Hand-Held Range 1.000 to 1.050 Automatic Temperature Compensation Yes Accuracy +/-0.0005 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 Specific Gravity 1.000 to 1.050 Features All Metal Housing Calibration Screw Glass Prism Non Roll Stand Rubber Eye Cup Rubber Grip Scale Display Single Hinged Daylight Plate Length 7 1/2 in