Very simple to use: place one drop of your sample on the prism and read the result on the scale immediately. Each refractometer is calibrated for measurements at 20°C (68°F), has the adjustable focus, a clear reading of the scale, and can be calibrated by screw. Models with Automatic Temperature Compensation (ATC) between +10 and + 30°C are suitable for applications where the temperature of the samples vary greatly. All models are provided in box, with cloth, screwdriver, pipette, pocket case and instructions for use.