The Walsin MT15N3R9B500CT is a type of Multilayer Ceramic Capacitor (MLCC). This MLCC is an SMD/SMT device with a capacitance of 3.9pF, a maximum working voltage of 50V, and a package size of 0402 (1005 metric). It is RoHS compliant, meaning it is free of hazardous substances and does not contain any lead. The MT15N3R9B500CT is mainly used for signal lines, radio-frequency (RF) circuits, automation, and high-frequency applications.