[. . . ] Important: With all large speakers, an initial "break-in" period is needed to perform at optimal levels. [. . . ] This stereo RCA input can be used to connect a CD, MP3, or other audio source. To connect to a portable device with a 1/8" headphone jack, you need a standard (1/8" to RCA) adapter which is NOT included. Master Volume Control: This knob controls the master volume of the Transactive Mobile. Power Adapter (IEC): Insert the included power cable here to charge the unit. Note that the Transactive Mobile can run off the power adapter while it simultaneously charges the battery. Voltage Selector: Set this to the correct voltage for your location standard. Power ON/OFF Switch iPod Charging Switch Battery Level Indicator: While the unit is powered ON, these four lights indicate the power left in the battery. Link Output: This ¼" jack is a stereo line level output that can be connected to the stereo input of an amplifier or amplified loudspeaker such as another Transactive Mobile. [. . . ] *Note: Battery life may vary based on temperature, age, and volume usage of product. [. . . ]