The bigger Inspire 1 Battery 5700 mAh battery is available to give you extended flight times, up to 22 minutes. The standard 4500 mAh battery yields 18 minutes. Thats a 22% increase in flight time with the bigger battery.
Note based on the total watt hours of this battery you cannot bring more then 2 of the 5700mah batteries onboard commercial airlines. Check the FAA website for guidelines on bringing LiPo batteries on airplanes, and ALWAYS take them into carry on. Pick up a high power DJI smart battery charger, giving 180W of charging versus the standard 100W and cut down on charge time dramatically.