The Mastercool Refractometer, No. 43705, offers a quick and easy way to test the freezing point of coolant and anti-freeze. This product is compatible with ethylene or propylene glycol and measures battery acid specific gravity. Other features include automatic temperature compensation, large easy to read graphics and high contrast lens adjustable focus viewfinder and strong metal body structure. The refractometer includes a storage case, fluid dropper and calibration screwdriver. This product is not for use with OAT coolants or DEF.