The 501-27516-12 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 5 MHz, Supply Voltage 15 V, Phase Noise -160 dBm/Hz@100 Hz to -145 dBm/Hz@10 Hz, Phase Noise 1 kHz -165 dBm/Hz, Phase Noise 10 kHz -165 dBm/Hz. Tags: Module with Connectors, Thru-Hole. More details for 501-27516-12 can be seen below.