The ECX-53B-DU from ECS Inc. International is a RF Quartz Crystal with Frequency 10 to 50 MHz, Frequency Stability ±100 ppm, Frequency Tolerance ±30 ppm, Drive Power Level 300 µW, Load Capacitance 8 to 20 pF. Tags: Surface Mount. More details for ECX-53B-DU can be seen below.