Product Description Automotive Fluid Refractometer PT60501 Tests the strength, density & frost resistance of battery fluids, coolants & windscreen cleaners Fitted with the ATC (Automatic Temperature Compensation) system that automatically adjusts to the proper temperature during operation to correct temperature discrepancies during use Tests both Ethylene & Propylene Glycol, battery acid & windscreen washer fluid Extremely easy-to-use and calibrate Uses ambient light only & does not require batteries or a power source