The ECS-36-S-4X from ECS Inc. International is a RF Quartz Crystal with Frequency 3.6864 MHz, Frequency Stability ±50 ppm, Frequency Tolerance ±30 ppm, Load Capacitance 20 pF, Equivalent Series Resistance 200. Tags: Thru Hole. More details for ECS-36-S-4X can be seen below.