The ECS-270-18-30BQ-DS from ECS Inc. International is a RF Quartz Crystal with Frequency 27 MHz, Frequency Stability ±100 ppm, Frequency Tolerance ±30 ppm, Load Capacitance 18 pF, Equivalent Series Resistance 30. Tags: Surface Mount. More details for ECS-270-18-30BQ-DS can be seen below.