The 501-27187a from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 2500 MHz, Supply Voltage 15 V, Phase Noise -106 dBm/Hz@100 Hz to -76 dBm/Hz@10 Hz, Phase Noise 1 kHz -131 dBm/Hz, Phase Noise 10 kHz -154 dBm/Hz. Tags: Module with Connectors. More details for 501-27187a can be seen below.