External power options and audio interface for versatile use External 3.7 5V lithium battery power conversion enables portable operation via a supply pad USB powered universal Micro USB 5V power supply provides flexible power from USB sources LED indicator shows Bluetooth mode with a long blue light for clear status 3.5mm stereo audio interface uses a standard 3.5mm jack to output stereo sound, compatible with headphones, amplifiers, and other devices Use scenarios Portable Bluetooth listening: power from a 3.7 5V Li battery and listen through headphones or portable speakers while on the go Desktop or travel setup: power via USB 5V supply for reliable operation with wired headphones or an external amplifier Home audio connections: connect to speakers or audio equipment via the 3.5mm jack to enjoy stereo sound from Bluetooth or wired sources