The 501-25399 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 4000 MHz, Supply Voltage 15 V, Phase Noise -96 dBm/Hz@100 Hz to -66 dBm/Hz@10 Hz, Phase Noise 1 kHz -123 dBm/Hz, Phase Noise 10 kHz -141 dBm/Hz. Tags: Module with Connectors. More details for 501-25399 can be seen below.