Compact brake fluid tester. It allows you to instantly measure the water content in the brake fluid, regardless of your car model. It is enough to dip the tester electrodes into the brake fluid reservoir and read the LED readings. The device is capable of testing several types of brake fluids (DOT 3, DOT 4, DOT 5, DOT 5.1). Material: plastic Power supply: 1x AAA battery Number of LED indicators: 5 Two steel electrodes Height: 15 cm Diameter: 2 cm Instructions: To test the fluid quality, turn on the device with the button on the top. Then remove the bottom cover and place the tip of the tester (two pins) in the brake fluid reservoir. Reading the test results: Green LED: brake fluid does not contain water. Yellow LED: less than 1% water in the system. Two yellow LED lights: 2% water in the system - Content within the norm. Red LED: 3% water in the system - fluid change recommended. Two red LED lights: more than 4% water in the system - BRAKE FLUID MUST BE CHANGED IMMEDIATELY! Tester maintenance: Replace the battery if the green LED does not light up after pressing the button on the "switch". Flashing red LED lights - replace the battery. The tester requires 1 AAA battery (not included). Clean the measuring pins under running water after each use.