The ECS-40-18-5G3X-JGN-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 4 MHz, Frequency Stability ±30 ppm, Frequency Tolerance ±20 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 150. Tags: Surface Mount. More details for ECS-40-18-5G3X-JGN-TR can be seen below.