The ECS-36-20-18-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 3.6864 MHz, Frequency Stability ±100 ppm, Frequency Tolerance ±30 ppm, Load Capacitance 20 pF, Equivalent Series Resistance 200. Tags: Surface Mount. More details for ECS-36-20-18-TR can be seen below.