The NAC1 from AccuBeat is a Rubidium Oscillator with Frequency 10 MHz, Supply Voltage 3.3 V, Power Consumption 1.2 W (Operation), 2.4 W (Warm-Up), Phase Noise -150 to -86 dBc/Hz, Short Term Stability 0.02 to 0.2 ppb. Tags: Drop-in. More details for NAC1 can be seen below.