FeaturesLargest & Sharpest Display Scale Available Exclusive Zero-Ring Requires No Calibration Tools Durable, All-Metal DesignVEE GEE® X-Series Handheld Refractometers are exceptionally simple to operate and provide quick, accurate measurements for the concentration of nearly any aqueous solution.Easy to Use. Operation consists of placing 1 or 2 drops of sample on the prism, closing the daylight plate over the sample, then looking through the focusable, cushioned-rubber eyepiece for the readings.Accurate. Featuring the largest, easiest-to-read scale available with clear, sharp figures, screen shading, and incredible contrast. These features significantly enhance overall accuracy even when several different operators use the instrument. All units feature rubber grips on the body, which block the transmission of hand heat to reduce temperature errors.Compact & Portable. The small size of the X-Series models allows them to be used anywhere the field, plant, or lab.Tool-Free Calibration. The VEE GEE® exclusive Zero-Ring eliminates the hassle of using a separate tool for calibration. Simply place a few drops of distilled water or liquid standard (R.I. oil or prepared sucrose solution) on the prism, turn the built-in Zero-Ring until the shadow line is at the correct value of the liquid, and secure the set screw that's itDurable. The X-Series models feature rugged construction to provide years of reliable use. The prism is mounted in an all-metal housing which allows the sample and prism to reach temperature equilibrium quickly. Also feature non-roll stands to ensure that once the units are placed on a table or bench top, they won't be prone to roll off the surface.Wide Selection of Scales & Ranges. Choose from Brix, Salinity, Refractive Index (nD), and Coolant (freezing points of Ethylene & Propylene Glycol, Battery Charge Level), Urea and NaCI.Automatic Temperature Compensation (ATC). Models BTX-1, BTX-20, STX-3, CTX-1, & CTX-2 feature ATC, which frees the user from having to re-calibrate in work environments with large temperature swings. The effective compensation range is 10-30°C.