... 3dB) Signal and noise ratio of power amplifier: =80dB Loud speaker: 1.77" (external diameter 45mm). Magnetic resistant 4Ohms Power ... colors, several solution, for your option. This compact travel speaker system is ideal for use at the office, home, carry where ... . You can enjoy sweet stereo sound product from the aluminum speaker. Several power supply manners including battery, computer USB, adaptor ...