Professional Brake Fluid Detection Pen: Specially designed for easy inspection of brake fluid quality. Put the tester in the water tank for a while and then the indicator light will show the result correctly. 5 LEDs show the result: 5 LEDs show the water content in the brake fluid. A water content of 1% to 2% means that the liquid is still usable and 3% to 4% means that you have to switch to a new liquid in order to drive safely. If the percentage is greater than 3%, replace the brake fluid. eley to use: Press the button above to turn on the tester. The green LED starts to light up. Hold the test rod in the brake fluid for a period of time. Then the LED will show the test result and the tester will automatically shut down after 12 seconds. Professional tool: The tester can be used as a digital brake fluid tester, which is suitable for determining the quality of brake fluid. Specially developed for professional use in car repair and maintenance workshops. Portable size: Compact, light and portable, it is a good helper for your travel. the LED light shows the amount of water in the brake fluid green: switch on / off green / yellow: less than 1% green / yellow / yellow: approx. 2% green / yellow / yellow / red: Approximately. 3% (time to change brake fluid.) green / yellow / yellow / red / red: Approx. 4% (Replace the brake fluid immediately ) Brake tester 5 LED display results: 5 LEDs indicate the percentage of water in the brake fluid. A water content of 1% to 2% means the liquid is still usable and 3% to 4% means you need to replace it with a new liquid to keep it safe. If the percentage is greater than 3%, replace the brake fluid. 5 LEDS: the 5 LED displays show the water content of the brake fluid in 5 steps from 0% to more than 3%. The brake fluid tester can be used for Dot 3/4/5 brake fluid (today the original brake fluid is Dot4 +). eley to use: press the button above to turn on the tester. The green LED starts to light up. Hold the test rod in the brake fluid for a period of time. Then the LED will show the test result and the tester will turn off automatically after 12 seconds. Professional tools: The tester can be used as a suitable digital brake fluid tester to determine the quality of the brake fluid. It was specially developed for professional use and the maintenance of auto repair shops. eley To Use: Press the Up button to turn the tester on. The green LED starts to light up. Place the test rod on the plastic in the brake fluid for one second. Then display the test result via the LED. Battery powered: powered by 1.5 V AAA battery (not included). Specification: Type: brake fluid tester Material: Led Compatible: All vehicles Battery: 1 * lr03 Aaa 1.5V battery (not included) cut; 15.5 * 2.5cm / 6.1 * 1 "(height * depth) Net Weight: 0.04kg / 1.4oz dot4 brake fluid Warning: The green light goes out. When you press the button, please replace the battery immediately. Clean the test needle with tap water after each use. If brake fluid comes into contact with your skin or clothing, wash the affected area with water. Do not expose the brake fluid to air for a long time, as it absorbs moisture a great deal.