S/N is a 32 digit authorization code for activation of controller functions.
We have already filled in the authorization code for your controller after manufacture. 
You might be asked to fill in a new S/N in the future 
if you brought new function upgrades (i.e. Waypoint etc.)
If you enter an invalid S/N more than 30 times, your controller 
will be locked and you have to contact our customer support.
