The 501-25503 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 10 - 8000 MHz, Supply Voltage 15 V, Phase Noise -97 dBm/Hz@100 Hz to -79 dBm/Hz@10 Hz, Phase Noise 1 kHz -115 dBm/Hz, Phase Noise 10 kHz -134 dBm/Hz. Tags: Module with Connectors. More details for 501-25503 can be seen below.