Item Name: Brake Fluid Test Pen Power Supply: 1 x 1.5V AAA Battery(Not Included) Suitable: for DOT3/DOT4 Test Features: Fine Workmanship, High Accuracy, Easy Operation Size Details: 15.5cm x 2cm/6.1" x 0.79" (Approx.) Specifications: The length of the product is 15.5cm, the diameter is 2cm. Colorful indicator light design is the outstanding feature of this brake fluid test pen, so it can directly and clearly display the status of the car brake liquid. Brake fluid testers are used to determine the quality of brake fluid. It is used to determine the change in moisture content of the brake fluid based on the change in electrical conductivity. The moisture content is clearly displayed by means of a light emitting diode. High levels of moisture will lower the boiling point and then affect the braking performance of the car. Red indicates that the brake fluid needs to be changed immediately, green indicates that the brake fluid is in good condition, and yellow indicates that the brake fluid is holding up well but will change. It is constructed of nylon material. This brake fluid test pen is practical, which can accurately measure the water content of the brake liquid to ensure safe driving. Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. 5 LEDs: 0% LED: water content in brake fluid. 1% LED: water content, H2O Less or Equal to 1%, brake fluid above standard. 2% LED: water content, H2O Less or Equal to 2%, can still be used. 3% LED: water content, H2O Less or Equal to 3%, the brake fluid is recommended to be replaced. 4% LED: water content, H2O More Than or Equal to 4%, brake fluid must be replaced. Package Includes: 1 x Brake Fluid Test Pen