Electro Kabuki dropper modules are internally hard-wired at the time of manufacture and designated as ‘Circuit 1’ or ‘Circuit 2’. The designation of each module is marked on the product label and stamped into the metal load-hook jaw.
If you’re rigging a simple drop, you will want all your dropper modules to actuate in one go. In this case, it makes no difference whether you use Circuit 1, Circuit 2 or a mixture of both. The firing box allows you to fire them all simultaneously.
Circuit 1 or Circuit 2 dropper module designation only becomes significant when you rig a more sophisticated reveal effect, like a flop and drop or phased drop (see the EK System page for configuration examples). And the good news is that you can still control these advanced effects from a single firing box, connected to the rig by just one cable.