Dayton Audio MARK1 Portable 2.1 Bluetooth Brick Speaker with Hands Free Calling High efficiency 2.1 speaker system delivers surprising output from a small package Play music anywhere for up to eight hours, thanks to the onboard Li-ion battery Built-in power bank keeps your devices charged while the speaker is on Large-surface woofer and tuned bass reflex enclosure produce loads of bass Pair using NFC (Near-Field Communication) technology with just a tap from your phone