Delivering metrology-grade time and frequency performance in configurable 1U rack-mountable package, SyncSystem 4380A employs internal rubidium oscillator and L1/L2 GPS receiver that mitigates effect of ionospheric delay changes and supports advanced GPS processing. Reference offers timing accuracy of <10 ns RMS, frequency accuracy of <1E-13 at 1 day, and holdover of 250 ns at one day. Six expansion ports for hot-swappable output modules provide array of timing signals.