1. The main function of this brake fluid test pen is to determine the quality of the brake fluid2. According to the change in electrical conductivity to determine the moisture content of the brake fluid change3. 5 LED lights display moisture percentage in brake fluid, provides more accurate test result4. Designed without cable connector, portable and lightweight, easy to carry and use5. Suitable for professional use in auto repair shops to test DOT3 / DOT4 / DOT5 fluid Specification: Description:< br/>This brake fluid tester is used to determine the moisture based on the change of conductivity and check the quality of car brake oil, it is used to test DOT3/DOT4/DOT5 fluid. />Features:The main function of this brake fluid test pen is to determine the quality of the brake fluid.According to the change in electrical conductivity to determine the moisture content of the change of brake fluid. 5 LED lights display the moisture percentage in brake fluid, provides more accurate test result. Designed without cable connector, portable and lightweight, easy to carry and store. use.Suitable for professional use in auto repair shops to test DOT3 / DOT4 / DOT5 fluid.Features:tat: NewMaterial: plastic, electronic componentsThe color is blackLength: about 155mm / 6.1inchWidth: 18 mm / 0.7 inchPower supply: AAA 1.5 V LR03 battery (not included)LED: 5Net weight: about 29gPackage weight: about 61gPackage list:1 * brake fluid tester (battery not included) Instruction:Unscrew the brake fluid reservoir and remove the cap from the brake fluid tester then immerse the test probes in the brake fluid up to the plastic edge of the device.Indication of product label:Green: Battery OK, i.e.: No water in brake fluid.Yellow: less than 1% water in brake fluid.Yellow/Yellow: approximately 2% of water content in brake fluid .Yellow / yellow / red: approximately 3% of the water content of brake fluid. Brake fluid needs to be changed.Yellow / Yellow / Red / Red: At least 4% water content in the brake fluid. The brake fluid must be changed urgently! Extreme Danger! Note: The data is manual measurement, please allow 1-141cm error, due to differences in light and screen, there will be a certain color difference, the specific received in kind prevail.