DY23/DY23B Car Brake Fluid Tester with LED Digital Indicator Checks DOT3 DOT4 DOT5 Car Oil Quality Portable size, can be operated with one hand Buzzer red light dual alarm, test results are clear at a glance Oil-resistant and anti-oxidation chrome-plated tester; 2.2-inch backlit LCD screen, intuitive interface Brake pressure is transmitted through brake fluid. If there is too much water in the brake fluid, the pressure transmission will no longer work. For safe driving, we need to regularly detect the water content in the brake fluid ratio scale. Brake fluid tester helps us with continuous maintenance work and allows us to drive safely. Operation Instructions: 1. Install a 9V (6F22) battery on the back of the tester. 2. After inserting the battery, press the POWER button to turn on the machine, all LED lights will light up, and the buzzer will sound, indicating that the product self-test is successful. 3. Press the SELECT button to automatically locate the DOT3 model. 4. Each time you press the SELECT button, the indicator LED will cycle from DOT3 to DOT4 to DOT5.1. 5. Immerse the probe in the brake fluid, you will see different colors of LED lights, they mean: Green light: Indicates that the brake fluid contains less than 1% water The first yellow light: Indicates that the brake fluid contains about 1.5% water The second yellow light: Indicates that the brake fluid contains about 2.5% water The first red light: Indicates that the brake fluid contains about 3% water The second red light: Indicates that the brake fluid contains more than 4% water 6. Press the POWER button to turn off the tester. Note: Due to the difference between light and screen settings, the color of the product may be slightly different from the picture. Please allow slight size differences due to different manual measurements. Shipping Quantity: 1 Piece