product description The brake fluid testing pen is used to test the quality of the brake fluid. The test result of the water content percentage of the brake fluid is displayed by the number of 5 LED lights on the test pen. The FT123 brake fluid testing pen measures the moisture content of the brake fluid according to the change in electrical conductivity, and clearly displays the moisture content through the light-emitting diode. High moisture content will lead to a decrease in the boiling point and affect the braking performance. A red light indicates that the brake fluid needs to be replaced, a green light indicates that the brake fluid is in good condition, and a yellow light indicates that the condition is acceptable. Features Powerful function, simple operation; accurate measurement, safe use; Detect all brake fluid; with automatic shutdown function; Can test DOT3/4/5 brake fluid. Product Instructions Green: power OK/no water; Green/yellow: moisture content is less than 1%; Green/yellow/yellow: water content close to 2%; Green/yellow/yellow/red: the water content is close to 3%, it is recommended to replace the brake fluid; Green/Yellow/Yellow/Red/Red: The water content is higher than 4%, dangerous, and the brake fluid must be replaced immediately. Note: The above data are for reference only; Battery: 1 AAA battery, open the battery cover according to the direction indicated by the arrow on the test pen. Notice 1. If the green LED light does not light up after pressing the power button for a long time, you need to replace the battery; 2. After each use of the test pen, please wash the test probe with clean water; 3. Please do not expose the brake fluid to the air for a long time, because the brake fluid has strong water absorption. Preparation before the test Unscrew the cap of the brake fluid reservoir and remove the cap of the test pen. Dip the test probe into the brake fluid in the reservoir. Moisture Test Press the power button, the green LED light will light up. Hold for 1 second, the test result will be displayed by the lighting of the LED light, after the test is completed, the test pen will automatically turn off after 12 seconds. Packing List: 1 x FT123 Brake Fluid Test Pen (AAA batteries not included) Return Policy All of our items come with a 30-day free return policy. If you need to return, please contact us, let us know the detailed problem and send us some pictures for confirmation. We reserve the right to refuse any returns for objective reasons. Shipping Policy All of our items are shipped free with tracking numbers. Orders will be shipped within 3 working days upon receipt of payment. Most orders will be shipped within 1 working day. In most cases, shipping takes 8-12 working days.