This convenient accessory fits inside the camera's battery compartment, and works with the optional AC Adapter AC-E6 to enable you to power the DSLR directly from a wall outlet for extended shooting time. This capability is useful when shooting in the studio for hours at a clip, since you won't have to worry about your battery running out of juice. Both the coupler and the AC-E6 adapter are included in the ACK-E18 AC Adapter Kit.