The DSX321G-16M SMD Crystal Resonators 16MHz ±20ppm SMD RoHS manufactured by KDS is an electronic component that consists of a quartz crystal that vibrates at a specific frequency, usually 16 MHz. It provides precise timing for the circuitry it is connected to, and is often used with the microprocessor-based devices. The package is an SMD (Surface Mount Device), making it suitable for board-level construction. The ±20ppm tolerance refers to the accuracy of the frequency determined by the crystal, while RoHS stands for Restriction of Hazardous Substances, ensuring that the resonators are manufactured without certain hazardous materials like lead.