The KBD040002020 with HC-49S-SMD-2P Crystals ROHS is a low-profile 4.0 MHz surface-mount crystal produced by KYX. It operates in the frequency range of 3.0 to 60.0MHz. It is constructed using two metal plates that are insulated with a dielectric layer. The two plates are arranged in parallel and connected to form a pierce oscillator with an adjustable frequency. The metal plates are etched with gold or silver plating, depending on the application, and separated by a dielectric layer to ensure an accurate and reliable oscillation. The crystal is manufactured with high-quality components and is designed to be resistant to extreme temperatures and vibration. It features low power consumption and low EMI, making it suitable for a range of applications including wireless communication, audio and video systems, and automotive electronics. It is also ROHS compliant and meets the requirements for lead-free applications.