Product Name: Brake fluid test pen The probe of the brake fluid test pen is made of high quality metal material to prevent oil and oxidation; the shell is made of black matte plastic for better slip resistance and overall excellent feeling. This product can quickly detect the health of your car's brake fluid and remind you to replace it when necessary, thus avoiding traffic accidents and making you more comfortable and safer. Features: 1. Easy to use, small size, easy to carry. 2. Metal probe: oil and oxidation resistant, not easy to corrode. 3. Shell: better anti-slip, good texture of the body. 4. 5 LED indicators show the percentage of water in the brake fluid. The 5 LED indicators will show the percentage of water in the brake fluid in green, yellow and red colors. It clearly shows the level of water contained through the light emitting diodes. A high water content will result in a lower boiling point and affect braking performance. Red indicates that the brake fluid needs to be replaced immediately, green indicates a good condition, and yellow indicates an acceptable condition but will be replaced soon. 1. Green LED=water content in brake fluid H2O<1.5%, brake fluid is qualified. 2. yellow LED=water content in brake fluid H2O=1.5% to 3%, can continue to use and test again after six months. 3. red LED = water content in brake fluid H2O>3%, can not continue to use, need to replace the brake fluid red LED: replace the brake fluid.