Description : This pen-shaped brake fluid tester can easily help determine if its time for you to change your brake fluid. Staying safe and knowing that your car is in top condition is most important. Great tool for checking brake fluid for your car. What should I do 1. Switch on the brake fluid tester by pressing the button. A green light should come on. If the light doesnt come on, it may be time to change a battery. 2. Unscrew the brake fluid reservoir cap and remove the brake fluid tester cap. 3. Immerse the probe tips in the brake fluid and the LED lights will show the percentage of water in the brake fluid. 4. After testing, tighten the brake fluid reservoir cap securely. 5. The tester will automatically turn off after 12 seconds of inactivity. NOTE: After each test, you must clean the test head with a dry cloth or paper. The LED lights indicate the water content in the brake fluid: - Green: None. - Green / Yellow: Less than 1%. - Green / Yellow / Yellow: Approx. 2% - Green/Yellow/Yellow/Red: Approx. 3% (time to change brake fluid). - Green/Yellow/Yellow/Red/Red: Approx. 4% (change the brake fluid immediately!). Please note - This brake fluid tester is calibrated only for DOT 4 brake fluid which is used in most vehicles produced since 2006. - Replace the battery if the green LED lamp does not light up after pressing the button. - Wash the test tip with tap water after each use. - In the event of skin contact with brake fluid, wash the affected skin or clothing thoroughly with water. - Do not leave brake fluid in the atmosphere for long periods of time as it is very hygroscopic. packing list 1 * Car Brake Fluid LED Tester Detector (Black) Note :Battery 1*LR03 AAA 1.5V battery (not included)