This refractometer has an exclusive scale for measuring specific gravity of battery fluid and for knowing freezing temperature of ethylene glycol and propylene glycol. These are used as antifreeze mixture for automobiles or thermal catalyst for solar power systems. This refractometer has an exclusive scale for measuring specific gravity of battery fluid and for knowing freezing temperature of ethylene glycol and propylene glycol. These are used as antifreeze mixture for automobiles or thermal catalyst for solar power systems.