Refractometer The ROB75240 Hand Refractometer is a portable, precision optical instrument used for measuring the freeze point of engine coolant and the operation state of battery charging liquid. . It is used on transportation vehicles, such as cars, tractors, tanks, ships, etc., which use propylene or ethylene glycol for coolant and sulphuric acid for charging liquid. . It can also be used for checking the strength of electrolyte solution batteries.. This precision instrument features high-quality optics with ultra-smooth focusing.. Scale range: 32DEG F to -60DEG F 75240 No -