The ECS-200-18-4X-CKM from ECS Inc. International is a RF Quartz Crystal with Frequency 20 MHz, Frequency Stability ±10 ppm, Frequency Tolerance ±10 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 30. Tags: Thru Hole. More details for ECS-200-18-4X-CKM can be seen below.