The ECS-120-18-23A-EN-TR from ECS Inc. International is a RF Quartz Crystal with Frequency 12 MHz, Frequency Stability ±50 ppm, Frequency Tolerance ±30 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 80. Tags: Surface Mount. More details for ECS-120-18-23A-EN-TR can be seen below.