OTC 3890 Brake Fluid Safety Meter Check condition of brake fluid in less than a minute Water can cause corrosion in system components and can vaporize under the high heat conditions of hard braking situations Boils a small sample of brake fluid in the reservoir to test for water contamination Will not operate if connected to the wrong polarity Works on DOT 3 4 and 5.1 fluids and uses no consumable test strips