AVR-M Chip Varistors TDK AVR-M Chip Varistors have no polarity, due to symmetrical current-voltage characteristics that are equivalent to Zener diodes. The AVR-M Varistors offer exceptional electrostatic absorption capability and are able to maintain symmetrical current-voltage characteristics even after electrostatic absorption. A wide 6.8V to 90V range of voltages are available with capacitances as low as 1.1pF.