Canon's external flashes with model numbers in the 400 range tend to be their mid-range external flashes. They all tend to have the ability to adjust the direction of the flash via a swivel head, which allows 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. The 400 series differs from the higher end 500 series mostly by lacking a remote controller.