The 501-27523-31 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 80 MHz, Supply Voltage 12 V, Phase Noise -136 dBm/Hz@100 Hz to -106 dBm/Hz@10 Hz, Phase Noise 1 kHz -166 dBm/Hz, Phase Noise 10 kHz -180 dBm/Hz. Tags: Module with Connectors. More details for 501-27523-31 can be seen below.