Feature: 1. Quickly test the quality of automobile brake fluid and check whether it is qualified. It can remind you to replace the brake fluid when necessary to avoid traffic accidents. 2. 5 LEDs display the percentage of water in the brake fluid. The LED indicator will display the percentage of water in the brake fluid in three colors, green, yellow and red. 3. Calibrated for cars using DOT4 and DOT3 brake fluid (but DOT3 is almost replaced by DOT4 because DOT4 has better performance). 4. Support automatic shutdown. It only takes a few seconds to know the result, very easy to use. 5. It is small in size, light in weight, does not take up space, and is easy to carry. It is a good helper for your journey. Specification: Item Type: Brake Liquid Tester Pen Material: ABS+Aluminium Alloy Color: BlackLength: Approx. 145mm/5.7inBattery Type: AAA alkaline battery (NOT Included)Fitment: Universal Instructions for Indicators:1. Green The battery is OK, there is no water in the brake fluid 2. Green / Yellow The water content of the brake fluid is less than 1%, and the brake fluid has good performance and can be used with confidence. 3. Green / Yellow / YellowThe water content of the brake fluid is about 2%, and the brake fluid can be used continuously. 4. Green / Yellow, Yellow / Red The water content of the brake fluid is about 3%. It is recommended to replace the brake fluid. 5. Green / Yellow / Yellow / Red / Red The water content of the brake fluid is at least 4%, the brake fluid needs to be replaced immediately. Test Steps: 1. Please change the battery when the red LED flashes 2. Turn on the switch when all the lights are on, please remove the battery to restart 3. After the switch is turned on, please release the button to measure. Package List: 1 x Brake Liquid Tester Pen