It gives you a good estimate how to gear your Electric Radio Controlled Helicopter.
It automatically fetching list of helicopters from MrMel's site so it's always updated with the updated list.
It will allow you to save preset (models) with your information which you can recall at any time.
It will also save last data used so you always come back with same info.
It can both give you estimated head speed or if you choose so it can give a suggestion of what pinion to use.
Do note that all values are estimated, true head speed may vary.
Add your quads or other machines and their associated batteries, once you do it, simply set your estimated battery flight time and start timer.
The phone will keep you informed about remaining battery time, so you can concentrate on flying.
You will also see statistics for number of flights, average flight time and total battery time.