The ECS-400-6-37-AGN-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 40 MHz, Frequency Stability ±30 ppm, Frequency Tolerance ±25 ppm, Load Capacitance 6 pF, Equivalent Series Resistance 50. Tags: Surface Mount. More details for ECS-400-6-37-AGN-TR can be seen below.