Features: 250mm Goose Neck Probe provides flexibility on detection, with its chromed surface, can be resistant to oils and oxidation; 3 LED lights show selected brake fluid types and 6 LED lights show percentages of water in the brake fluid. Brake pressure was transmitted by brake fluid, the pressure transmission will be out of function once brake fluid including too much water. Universal fit for most vehicle. High precision to test DOT-3, DOT-4, DOT-5.1 brake fluid. Small size, perfect hand-feeling. Buzzing and red light double alarm system, test result is clear absolutely. In order to safe-driving, we must test water ratio scale in brake fluid regularly. The brake fluid tester helps us do current maintenance, make sure we drive in safe condition. Specifications: Material: ABS+Metal Power Supply: 9V Length of goose neck probe: 250mm/9.8in Operating Steps: Step 1: Install a 9V battery (6F22) on the back of the brake fluid tester. (Batteries not included) Step 2: After inserting the battery, press POWER to turn on, all the LED lights are on and the buzzer sounds, indicating that the product self-inspection is successful. Step 3: Press the SELECT button to automatically place DOT3. Step 4: Every for time you press the SELECT button, when the LED indicator is on, it will switch from DOT3 to DOT4 and then to DOT5.1. Step 5: Immerse the probe in the brake fluid. Package Includes: 1X Brake Fluid Tester note: Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item.