NGS Roller Drum, 13.3 cm, 20 W, Wired & Wireless, USB Type-A, Black, Rotary NGS Roller Drum. Driver diameter: 13.3 cm. RMS rated power: 20 W. Connectivity technology: Wired & Wireless, USB connector type: USB Type-A. Product colour: Black, Volume control: Rotary, Display type: LED. Recommended usage: Universal, Audio formats supported: MP3, Compatible memory cards: MicroSD (TransFlash)