Power Packs & Heads
Power packs are made to accept and power numerous flash heads by extension cables. Some systems allow uneven distribution of power from each outlet to the flash heads.
Through other equipment you can determine where the light will fall and how focused or diffused it will be, but multiple heads with strategically positioned, modified lights can give you professional looking photos. The efficiency of the components, design of the circuitry, lamp head, type of flash tube, length of cables, reflectors and other accessories used will affect the performance of the pack.
When buying electronic flash equipment, light output is a major factor, but there are many others that determine the light exposing the subject and a power pack and flash head doesn't take them all into consideration.
Flash head kits with various accessories can cost up to $5,000.