Portable Speaker (Charge 4) Sound power and listening pleasure Play and charge endlessly Bluetooth mode Active mode (USB) or memory card AUX connection Power Source : USB (DC + 5V) (R.M.S: 3W) - "RMS refers to Root Mean Square which is a typical measurement of sound power, or rather, electrical energy transmitted from speaker to speaker, which is measured. Ha watts." RESISTANCE:4 nearly 4 hours of playtime Rechargeable lithium battery can charge your phone through the USB port Your first assistant Charge 4 on trips and go to the beach or swimming pool Excellent sound.Durable material you can take the speaker to anywhere and any adventure without worry.