Dodge SRT Hellcat Owner's Manual page 317

If your vehicle is equipped with the 6.2L supercharged
engine, it will support an additional engine power level
configuration as part of SRT Drive Modes. Use of the
RED key FOB unlocks the full potential of the engine's
output, and allows the driver to select from two power
levels within Drive Modes Set-Up.
Black Key FOB
UNDERSTANDING YOUR INSTRUMENT PANEL 315
Use of the BLACK key FOB limits the driver to a reduced
engine output. This information is also available within
the SRT Drive Modes interface, and can be accessed by
pressing the "KEY FOB" button on the touchscreen in the
SRT Drive Modes menu.
Drive Modes
Drive Modes
4