The 14D181K with Varistors 150V 300V 4.5KA Through Hole RoHS is a device manufactured by Hongzhi which is used to protect circuits from high voltage, electromagnetic interference, and power surges. It is a non-linear resistor with a low resistance between terminals above a certain voltage called the breakdown voltage. When the voltage exceeds the breakdown voltage, the resistance increases exponentially, allowing excess current to be diverted away from the circuit. The 14D181K Varistor has a rated breakdown voltage of 150V to 300V, with a maximum peak current of 4.5KA, and comes mounted in through-hole packages in accordance with RoHS standards.