The ECOXGEAR SolJam is a compact and loud waterproof Bluetooth speaker with integrated high efficiency solar charging panel technology. With a rechargeable battery and a high efficiency solar panel, you can play music all day. It has a waterproof (IP67), floating, rugged, drop-proof design. It has two 10-watt speakers for optimized stereo sound and a large subwoofer for enhanced bass. Connect an audio device using the 3.5mm cable connection or connect to your smartphone via Bluetooth. When connected to the AUX-IN connection, volume level must be controlled from the audio device. The SolJam has a separate master power switch and standby button. When not in use for extended periods, you can turn the master power off to preserve battery life. Charge the SolJam using a USB connection to your computer or to a power outlet using a USB to AC power adapter, or use the solar panel. The solar panel will recharge the battery while the SolJam is on or in standby power mode. The efficiency of the solar charging varies based on a variety of factors, including angle of the sun, global location, time of day, time of year, cloud cover. While playing audio, the SolJam can be charged or charge your device. Battery play time will be reduced depending on the time and size of the device charging while connected to the SolJam. Device charging rates are similar to the charging rate when connected to the USB of a desktop PC (approximately 3-hours for most smartphones, depending on device, battery specifications, etc.).