The 501-27515-31 from Wenzel Associates is a OCXO with Frequency 200 MHz, Supply Voltage 12 V, Phase Noise -123 dBm/Hz@100 Hz to -93 dBm/Hz@10 Hz, Phase Noise 1 kHz -148 dBm/Hz, Phase Noise 10 kHz -160 dBm/Hz. Tags: Module with Connectors, OCXO. More details for 501-27515-31 can be seen below.