Features 1.The brake oil detection pen measures the change in moisture of the brake oil based on the change in conductivity. 2.It clearly shows the degree of moisture content through the LED. High water content will cause the boiling point to decrease, affecting the braking performance, and corrosion of the brake master cylinder and the sub-pump, causing rust and seizure. 3.Red light indicates that the brake oil needs to be replaced immediately, green light indicates good condition, and yellow light indicates that the condition is acceptable, but it is about to be replaced. 4.This product can be used by car 4S shop and owner, the product operation is simple, accurate and fast! 5.Suitable for a variety of models, easy to use. Specification Features: The brake oil detection pen measures the change in moisture of the brake oil based on the change in conductivity. It clearly shows the degree of moisture content through the LED. High water content will cause the boiling point to decrease, affecting the braking performance, and corrosion of the brake master cylinder and the sub-pump, causing rust and seizure. Red light indicates that the brake oil needs to be replaced immediately, green light indicates good condition, and yellow light indicates that the condition is acceptable, but it is about to be replaced. This product can be used by car 4S shop and owner, the product operation is simple, accurate and fast! Suitable for a variety of models, easy to use. Detailed Description of the Indicators: Green: The battery is OK, that is, the brake oil does not contain water. Green/yellow: The water content in the brake oil is less than 1%, the brake oil performance is good, and you can use it with confidence. Green/yellow/yellow: The brake fluid has a water content of about 2% and the brake fluid can continue to be used. Green/yellow/yellow/red: The moisture content in the brake fluid is about 3%. It is recommended to replace the brake fluid. Green/Yellow/Yellow/Red/Red: The brake fluid contains at least 4% water, and the brake fluid needs to be replaced immediately. Tips: After each test, wipe the liquid part of the test point with a dry cloth or paper. Specifications: Condition: Brand New Material: Plastic Color: Shown as picture Battery: 1 * AAA Battery（not included） Weight: Approx.38g/1.3oz Package List: 1* Detection Pen (Battery is not included) Package List