The BG-E13 battery grip, which was made to be used with the 6D, allows the use of six AA cells, or one or two LP-E6 batteries. The 6D has a maximum burst frame rate of 4.5 frames per second. Like all Canon DSLR full-frame cameras, the 6D does not have a built in flash due to the design of the viewfinder.

What's the best answer to this question: does canon eos 6d have built in flash?
no