The 500-27991 from Quantic Wenzel (Wenzel Associates, Inc.) is a OCXO with Frequency 10 MHz, Supply Voltage 15 V, Output Power 12 dBm, Phase Noise -162 to -108 dBc/Hz, Phase Noise 1 kHz -161 dBc/Hz. Tags: Thru-Hole. More details for 500-27991 can be seen below.