Dimmer packs are what you plug your lighting fixtures into in order to dim them. Though dimmer packs ultimately do the dimming, the dimming is controlled by an external controller. On the most basic dimming packs, what you plug into a dimmer is the fixture’s power cord into one the Edison AC jacks. Dimmer packs will also have XLR inputs and outputs for DMX512 and/or other protocols. These inputs are to be used when you are daisy-chaining, or linking together, multiple dimmer packs under the control of the controller.