Anti-freezing solution (coolant) which main ingredient is ethylene glycol is widely used as mixed in cooling water of car's radiator, as cooling medium for central air - conditioning system, freezer / refrigerator, cooling coil, cooling fixture, and so on. The "Pocket" coolant refractometer can easily measure the coolant in brine and other agents of Ethylene Glycol. Measured value displayed digitally. The freezing point of the sample can also be measured and displayed.