The ECS-400-10-37-CKM-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 40 MHz, Frequency Stability ±10 ppm, Frequency Tolerance ±10 ppm, Load Capacitance 10 pF, Equivalent Series Resistance 50. Tags: Surface Mount. More details for ECS-400-10-37-CKM-TR can be seen below.