Portable speaker provides a sound system for meeting,teaching, training,outdoor activities like wedding,Yoga classroom even for tourist guide,elder and whisper etc. Voice amplifier supports MP3 audio playing and TF (Micro SD) card playing & USB flash driver playing. Can repeat single tune, loop all music and switch songs. Portable Loudspeaker built in rechargeable lithium polymer battery. Continously working time is up to 6 to 8 hours. You can use USB cable included to charge this mini voice amplifier. Only needs 3~5 hours to fully charge it. Microphone and speaker compact size (7.087 x 5.669 x 2.205 inches) and light weight (11.36 ounces). Voice Amplification System comes with an adjustable band you can use around your waist but also has a clip on the back of the unit you can clip on a belt or pant waistband. Portable voice amplifier is a life saver on your voice and throat!Speaker gives off a clear and crisp sound,no noise and no distortion!You could easily make a presentation to a group of 50 people and be heard clearly.