Zoweetek SHIDU Portable Rechargeable Mini Voice Amplifier With Wired Microphone Headset and Waistband for Teachers, Tour Guides, Coacher, Singing, Training and Presentation (S308-Black) Double magnets sound unit and professional sound amplifying circuit provide clear and crisp sound. The max 5 watts sound can covers 5000 square foot (500 ), no distortion and no howling phenomenon. Supports MP3 audio playing: TF (Micro SD) card playing & USB flash drive playing. Can repeat single tune, loop all songs and switch songs. You can use voice amplification at the same time when playing music, which is fit for singing, dancing and yoga. When playing music, the "A-B" part repetition function can intercept a section of music, then loops this section of music. It can be used for reading, listening and writing, which is fit for teaching and singing. Built in rechargeable lithium battery. The working time can be up to 12 hours. You can use mini USB cable to charge this voice amplifier. The wired headworn microphone is adjustable. You can adjust the distance between your mouth and the mic. Compact size (4.33 x 3.46 x 1.50 inches) and light weight (0.3 lb). You can use the back clip to fix it on your belt or pocket. You can also use waistbelt to tie it around your waist or hang it on your neck. Suitable for teacher, trainer, coacher, tour guide, shopping mall, presentation, outdoor speech and etc..