The HEL-10D471K is a varistor with a surge current rating of 2.5kA and a working voltage rating of 470V to 775V, designed to protect electrical equipment against transient voltage spikes. It is manufactured by Hongzhi, and comes in a through hole package. It is also RoHS compliant, meaning that it does not contain hazardous materials such as lead, mercury, and cadmium.