The 501-25900b from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 100 MHz, Supply Voltage 15 V, Phase Noise -138 dBm/Hz@100 Hz to -108 dBm/Hz@10 Hz, Phase Noise 1 kHz -163 dBm/Hz, Phase Noise 10 kHz -188 dBm/Hz. Tags: Module with Connectors, Low G-Sensitivity. More details for 501-25900b can be seen below.