[Quality] After much research on similar products on the market, the new brake fluid pen tester is the perfect tool for updating. The readings are more accurate during testing. In the at the same time, its material Housing is made of high quality nylon compared to ABS material. This product is more resistant to corrosion and has a longer lifespan. (battery not included) [LED Light] Red indicates the need to change the brake oil immediately, green indicates good condition and yellow indicates normal, but this changes the water content clearly displayed by the light emitting diodes (LED) . Brake Fluid] The brake fluid detector works immediately to check the quality of the brake fluid and provides ready results in the form of a color LED display. The rapid brake fluid quality test measures the content in water from the brake fluid to assess vehicle safety. You don't have to wait long to read it. The result only appears after a few seconds of immersing the pen in the liquid. [Test vehicle] This brake fluid tester is suitable for 4S shops and car owners. It's simple, precise and fast. [Brake oil detector] brake fluid absorbs moisture. Over time, moisture is gradually absorbed. You should change the brake fluid regularly based on the test results.