The 501-26959a from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 250 MHz, Supply Voltage 15 V, Phase Noise -122 dBm/Hz@100 Hz to -92 dBm/Hz@10 Hz, Phase Noise 1 kHz -150 dBm/Hz, Phase Noise 10 kHz -176 dBm/Hz. Tags: Module with Connectors. More details for 501-26959a can be seen below.