The ECX-P27CM-644.5313 from ECS Inc. International is a General Crystal Oscillator with Frequency 644.5313 MHz, Supply Voltage 2.5 V, Current 68 mA, Frequency Stability ±25 ppm, Operating Temperature -20 to 70 Degree C. Tags: Surface Mount. More details for ECX-P27CM-644.5313 can be seen below.