10D391K with Varistors 320V 650V 2.5KA Through Hole RoHS manufactured by Hongzhi is a type of electronic component. It is a single inline radial lead varistor with a voltage range of 320 volts to 650 volts, a rated current of 2.5KA, and a through hole mounting type. The component is RoHS compliant, which means it does not contain any hazardous materials, and is manufactured by Hongzhi.