This kit provides a comprehensive set of equipment ideal for close up and some portrait photography. It takes the place of conventional ring flash gear and is both more flexible and more useful than a ring flash.
The kit contains the Su 800 commander unit. This works as the controller for however many SBR-200 flash units you are working with. I use up to 6 such units for delicate close-up work. The flash units can be mounted on a ring that screws onto the lens [the kit contains a variety of different ring sizes] or mounted remotely on small stands [also supplied] to provide fill-in flash or to illuminate backgrounds etc.
It is worth noting if you own one of SB-600, SB-800 or SB-900 flash guns, then these can be used in place of the SU 800 commander unit as they have the commander facility built in. Similarly, more recent Nikon cameras with pop-up flash [D300, D700, D90 etc] have the capability of acting as commanders. This system works well and you might want to consider going down that route; various kits are available from Nikon that don't include the SU-800 commander unit and are cheaper than this complete kit.
In practice, the system works extremely well, providing a highly flexible set of lighting options. The learning curve is quite steep initially [stuff about sets and groups etc] and you might find a book on the subject [I suggest Mike Hagen's Nikon Creative Lighting System] to be helpful in fleshing out the instruction manual.
I'm a professional photographer and have no room in my outfit for things that don't help me be more creative and productive. On that basis, this kit has more than earned its place in my camera bag.