The 501-25721 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 1000 MHz, Supply Voltage 15 V, Phase Noise -109 dBm/Hz@100 Hz to -77 dBm/Hz@10 Hz, Phase Noise 1 kHz -136 dBm/Hz, Phase Noise 10 kHz -154 dBm/Hz. Tags: Module with Connectors. More details for 501-25721 can be seen below.