The ECS-120-18-20BQ-DS from ECS Inc. International is a RF Quartz Crystal with Frequency 12 MHz, Frequency Stability ±100 ppm, Frequency Tolerance ±30 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 60. Tags: Surface Mount. More details for ECS-120-18-20BQ-DS can be seen below.