The Sync-Circuit module synchronizes SpectrAlert Advance strobes at 1 Hz and horns and chimes at temporal 3 over a single pair of wires. Patented module technology also allows the silencing of horns or chimes on horn/strobe and chime/strobe models over a pair of wires.

The MDL3 Module is designed to work with the SpectrAlert and SpectrAlert Advance series of notification appliances to provide a means of synchronizing the temporal-coded horns and chimes, synchronizing the one-second flash timing of the strobe, and silencing the horns and chimes of the horn/strobe and chime/ strobes combination over a two-wire circuit while leaving the strobes active.