The future is here: 4 TTL flashes with RF wireless operation ...

FERNANDO FERRAZ, EXPLORA:

Over the last few years, we have seen releases from Canon, Nikon, Sony, and Profoto that have slowly but surely spread the use of built-in radio transmission to nearly all TTL flash systems. These speedlights are ideal for those who regularly use several flashes off the camera, working seamlessly with connected units up to 90' away and even farther, in some cases. Walls and objects blocking your way? Not a problem, because radio frequencies pass through obstacles and do not require a direct line of sight the way optical systems do.

In short, forget about fumbling with cables: radio-equipped flashes are the best lighting solution for compact photography kits, and are here to stay.

Check it out, from here.