Canon has updated their flagship (flash-ship?) flash unit to the 600EXII-RT! The new model gives a modest increase in continuous flash performance, up to 1.5x speed over the previous 600EX-RT flash. A higher resolution LCD screen and slightly redesigned menu promotes an easier to understand menu system. The new flash also comes with a foot with 1/4"-20 thread underneath, bounce diffuser, a dark orange (CTO) Gel cap, and a light orange (1/2 CTO) Gel cap.
Batteries not included.
Speaking of batteries: