The approved method of testing the water content of brake fluid. Just 3% of moisture can lower the brake fluid boiling point by over 100C. The best way to detect this small water content is to measure the boiling point of the fluid. The unit incorporates a heater element, LCD display and a power lead for use on 12V DC power supplies. Works on DOT 3, 4, 5 and 5.1 specification fluids. Supplied in storage case with full operating instructions.