Photogenic Flashmaster series power packs require Power Ratio Plugs -- small power regulators -- which are inserted into the power pack, for the purpose of dividing the power output of each channel to the flash heads.
The plugs allow full, 3/4, 2/3, 1/2, 1/3, 1/4, and 1/8 power levels to be distributed asymmetrically to each flash head connected to the power pack. These plugs are listed individually, or in sets.
Note: This is an outdated system. Photogenic suggests you call for availability before you place an order. 800-682-7668 , 8:00 AM to 5:00 PM EST.