Want to impress your neighbors or if you lose your your Phantom/Inspire?
Other than putting your FAA number inside in the battery compartment and/or on the battery so some nefarious person doesn't copy it and use it for their own so you get blamed for any rule breaking you can also put another label on the outside. I have both;

On the inside I put my phone number below the FAA #, so that hopefully, they call me (maybe they'll think that's the FAA office number) before they contact the FAA if for some reason I crash or have a flyaway.
Other than putting your FAA number inside in the battery compartment and/or on the battery so some nefarious person doesn't copy it and use it for their own so you get blamed for any rule breaking you can also put another label on the outside. I have both;
FAA Authorization:
U.S. PL112-95US A-91-57
Reward Call xxx-xxx-xxxx
All that is, is Public Law, FAA Modernization and Reform Act, as it applies to model aviation but it looks kinda official. U.S. PL112-95US A-91-57
Reward Call xxx-xxx-xxxx

On the inside I put my phone number below the FAA #, so that hopefully, they call me (maybe they'll think that's the FAA office number) before they contact the FAA if for some reason I crash or have a flyaway.