1) Extreme Low E.S.R.:less than 0.002W; 2) Auto on/off four-digit display; 3) LED indicator lights; 4) Electronic Polarity Protection Circuit; 5) Over-voltage Protection Circuit; 6) Normal working temperature:minus 40°C to 95°C; 7) Mounting brackets & hardware included; 8) Optional digit color: red, blue & white 9) Available in: 0.5F, 1.0F, 1.5F, 2.0F, 3.0F, 4.0F