From the Manufacturer:
The Profoto Pro-B4 1000 Air Generator is the fastest, toughest, most precise battery generator on the market.
Extremely Short Flash Durations
With flash durations down to 1/25,000s, the Pro-B4 offers the shortest flash durations of any generator on the market. It is now possible to freeze motion in a way that yesterday’s photographers could only dream of.
Exceptionally Fast Recycling
The Pro-B4 is the fastest recycling battery generator on the market. At lower power settings it is able to fire up to 30 flashes per second, while the longest wait on full power is less than a second. In other words: you will never have to wait for the Pro-B4. Now how fast you can shoot depends only on your camera.
The solid-cast aluminum chassis and the sturdy rubber frame ensure that the Pro-B4 can take a beating. All connection are covered with protective lids, helping to prevent moisture and dust from entering the generator.
Powerful Inside and Outside the Studio
On-location, its performance rivals that of any mains-powered studio generator. In the studio it gets even better. The battery can fully recharge in less than 45 minutes and can be recharged while in use! This means that if the modeling light is used moderately, the pack can be used continuously.
Extraordinary Power Range and Superb Precision
The Pro-B4 offers a huge 11 f-stop power range with unrivaled stability in power output and color temperature. It has two independent outlets with individual and intuitive controls and displays.
Integrated Air Radio Sync and Remote
The unique Air system is the fastest radio sync system in the world. Control the Pro-B4 from your camera, your computer or from the palm of your hand.