The ECS-120-18-33-AEN-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 12 MHz, Frequency Stability ±50 ppm, Frequency Tolerance ±25 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 100. Tags: Surface Mount. More details for ECS-120-18-33-AEN-TR can be seen below.