This chip is a metal-oxide varistor (MOV) made by the Chinese company Ruilongyuan. It is a 0402 package, meaning that it is 0.04 inches square and 0.02 inches high. The rating for the chip is 18V 50V, meaning that it can handle a surge of up to 50 Volts before breaking down. It is RoHS compliant, meaning that it does not contain any hazardous materials. It is mainly used in the design of circuits which can protect against voltage spikes.