The 501-27500-25 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 5 MHz, Supply Voltage 12 V, Phase Noise -155 dBm/Hz@100 Hz to -135 dBm/Hz@10 Hz, Phase Noise 1 kHz -165 dBm/Hz, Phase Noise 10 kHz -165 dBm/Hz. Tags: PCB Mount, Thru-Hole. More details for 501-27500-25 can be seen below.