The ECS-50-18-4XEN from ECS Inc. International is a RF Quartz Crystal with Frequency 5 MHz, Frequency Stability ±50 ppm, Frequency Tolerance ±30 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 120. Tags: Thru Hole. More details for ECS-50-18-4XEN can be seen below.