The 501-27511-53 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 80 MHz, Supply Voltage 15 V, Phase Noise -135 dBm/Hz@100 Hz to -105 dBm/Hz@10 Hz, Phase Noise 1 kHz -155 dBm/Hz, Phase Noise 10 kHz -170 dBm/Hz. Tags: PCB Mount, Thru-Hole, Low G-Sensitivity. More details for 501-27511-53 can be seen below.