Item no.: IS20 with external adapter Specification: Output power:2W 2'' magnetically shielded full range drivers Illuminated blue LEDs on transparent panels Power on/off and volume control 7.5 volt AC/DC power adapter included, UL/CUL or CE/GS listed Dimension: 115x80x195mm(WxDxH) regular USB Specification: Output power: 1W 2'' magnetically shielded full range drivers Illuminated blue LEDs on transparent panels Power on/off and volume control Regular USB plug with signal cable Dimension: 115x80x195mm(WxDxH) true USB Specification: Output power: 1.2W 2'' magnetically shielded full range drivers Illuminated blue LEDs on transparent panels Power on/off and volume control Over+100dB SNR Powerful EQ sound effect 5.1CH virtual sound USB v1.1 connector Dimension: 115x80x195mm(WxDxH)