ST-030 wireless sound system with USB/SD port. This portable 50W amplifier is ideal for presentations at events, schools, associations, etc. Can be used everywhere, even without an AC outlet, because of a built-in battery. The operating range of the VHF handheld microphone is approximately 50 meters under ideal conditions. With Echo, 3.5mm audio input, sunken antenna and MP3 operation. Comes with shoulder strap.