The Canon Speedlite 600EX II-RT Flash is the same as its predecessor in almost every way but features a few key upgrades:

• 1.1-1.5x increased continuous flash firings and improved weather/dust resistance.
• Revamped flash control algorithm with a redesigned Quick Flash function that helps to minimize unfired flashes for more reliable, continuous operation.
• Overhauled menu for more intuitive use, along with a battery level indicator.
• Improved flash-readiness indicator.

This compact lighting unit can be mounted onto the hot shoe of your Canon camera or fired wirelessly from either your camera's built-in flash optically or via radio with an ST-E3-RT transmitter. It is also compatible with PocketWizards/Radio Poppers. Radio transmission allows for easy transmitter/receiver communication between other 600 EX-RTs/II-RTs or with the ST-E3-RT transmitter, even when the masters and slaves are not in line-of-sight of each other. This, along with a wide range, control over a large number of flash groups, and a wide and long zoom, makes this flash the perfect choice for wedding photographers working alone or with assistants. It is also ideal for portrait and travel photographers who need to create the biggest light possible from a very small unit.