Milwaukee Hand Held Refractometer 

The Milwaulkee hand held refractometer is a precision optical instrument used for measuring concentrations of substances in aqueous solutions. It works using the principle of light refraction trough liquids. 

When passing light trough a liquid the refracted angle will be shown on the scale determining the amount of dissolved solids in the liquid, letting you find how your plants are utilizing the nutrients.

Very simple to use: simply place one drop of your sample on the prism and read the results on the scales immediately! Factory calibrated and adjusted to measure at 68°F (20°C).

The Milwaukee Hand Held Refractometer has adjustable focus, easy to read numbers for good resolution and zero adjustment screw for calibration. Two year warranty.