Feature: 1. WORKING PRINCIPLE: Determine the moisture change of brake oil according to the change of conductivity, the brake fluid tester is convenient and practical. 2. LED INDICATOR: Clearly displays the moisture content through the LED, the high moisture content will lead to lower boiling point and affect braking. 3. DETECTION RANGE: The test pen has a detection range of 0%‑4%, detection types of DOT3, DOT4 and DOT5.1, has high accuracy and low error. 4. PLASTIC SHELL: The shell of the brake fluid tester is made of ABS, with good toughness, corrosion resistance, aging resistance and long service life. 5. PORTABLE DESIGN: The brake fluid liquid tester is a pen type design, which is convenient to hold, easy to use and carry, and has a wide range of applications. Specification: Item Type: Brake Fluid Tester Model: HT662 Material: ABS Battery: 2 x 1.5V AAA battery (not included battery) Purpose: Brake fluid detection Basic Parameters: Detection Range: 0%-4% Error: ±0.3% Test Type: DOT3, DOT4, DOT5.1 Operating Environment: Operating Temperature: 0-40℃ Storage Temperature: -10-50 ℃ Humidity: ≤95% Altitude: ≤2000 meter. Package List: 1 x Brake Fluid Tester 1 x User Manual