The 501-27304a from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 12000 MHz, Supply Voltage 15 V, Phase Noise -88 dBm/Hz@100 Hz to -58 dBm/Hz@10 Hz, Phase Noise 1 kHz -112 dBm/Hz, Phase Noise 10 kHz -137 dBm/Hz. Tags: Module with Connectors. More details for 501-27304a can be seen below.