The SP-HF150 is a USB powered speaker with four watts of total RMS power, delivering clear vibrant sound and deep bass reverberation. Even with a small package design, SPHF150 produces amazing sound quality and transforms your computer into a superb hi-fi stereo sound system. You can use it just about anywhere with your notebook or PC. Simple to set up and control, these speakers make it easy to enjoy your music, movies and games. Just insert the USB plug to a PC/notebook for power and the 3.5mm audio plug into your music playback device. Key Features RMS (Watts) 4 Signal-to-Noise Ratio 70dB Frequency Response 200~ 20K Hz Power Source USB Colour Black Volume Control Yes Power ON/OFF Yes Dimensions (WxHxD) 85 x 130 x 83 mm Weight 623g.