The ECS-500-18-33-AGM-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 50 MHz, Frequency Stability ±30 ppm, Frequency Tolerance ±25 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 40. Tags: Surface Mount. More details for ECS-500-18-33-AGM-TR can be seen below.