Canon's external flashes with model numbers in the 500 and 600 ranges tend to be their high end external flashes. All three products so far have included a controller that enables wireless control of other flashes. Another common feature is the ability to adjust the direction of the flash via a swivel head. The swivel properties allow the photographer to bounce the flash off walls, ceilings, and other objects, diffusing the light that hits the subject and reducing the harsh shadows associated with on-camera flash.