This Canon 580EXII Flash With Mini Litetrek Battery and Cable Kit from B&H Photo gives you one less thing to worry about when you have an extended shoot on location with flash. The Canon 580EXII is a top-of-the-line flash for the EOS system, with a guide number of 190' (58 m) at ISO100 at the 105mm focal length. It's compatible with E-TTL II, E-TTL, TTL, and manual exposure, with a 20% shorter recycling time compared to the previous version.
The Mini Litetrek Battery Pack can give you up to 650 flashes at full power or 3500 flashes at 1/64 power, with recycling times from 1 to 3.5 seconds. The battery can be removed from the power module, so that exchanging a depleted battery for a fresh one is only a matter of seconds. The power module has two outlets. A Canon-compatible cable is included.