Feature●Propylene Glycol Hydrometer Tests freezing protection level of all propylene glycol-based anti-freeze, and heat transfer fluids●Determines the freezing levels of all propylene glycol anti-freeze●Maintains fluidity in cold temperatures●Long fluid life●Controls carbon and varnish to help reduce depositsDescription Comstar’s Propylene Glycol Hydrometer Tests freezing protection level of all propylene glycol-based anti-freeze, and heat transfer fluids. Good to test the following PG-based ComStar products: Geothermal-PG, Freeze Free, Freeze Safe, and all ProFrost anti-freeze/chiller heat transfer products.