Cycle Sounds Rock Box User Manual page 2

*WARNINGS
Always make sure the rubber covers for the AUX and USB ports are
closed when not in use to avoid collecting moisture or debris. Also
make sure to remove devices and secure the rubber door covers
when encountering any moisture to avoid damage to the unit.
Failure to follow these instructions will result in your warranty
being VOID if water enters the unit due to not properly securing
the rubber covers.
*
The Rock Box output is designed for the high level input of an
amplified speaker system. Do not plug headphones into the Rock
Box or you may damage the unit.