For an easier usage, NEI and WAILA could be installed, which show the input and output on the Synchronizer.
The Synchronizer has one output side, two input sides and one "lock" side for red alloy cables, redstone, an adjacent circuit, machine, lamp or anything that can be controlled with redstone signals.
In the ground state the gate don't transmits a redstone signal. If a redstone signal reaches one input side, then also no signal is transmitted. But if a second redstone signal reaches the other input side, then one short redstone pulse is transmitted on the output side. For a second redstone pulse, the signals on the input sides must be terminated and reach the gate again.
If a signal reaches the "lock" side, the gate is locked and no signal is emitted at the output until the lock is released.
Using the screwdriver from Project Red, the orientation of the gate can be changed freely in all four directions.