Zoweetek 18W Rechargeable Portable Voice Amplifier with Wired Microphone Headset and Waistband, Supports MP3 Format Audio Playing for Teachers, Tour Guide, Coaches, Training, Presentation (M512-Blue) Amplifies your voice. The sound is clear, crisp, no noise and no distortion. The max 18 watts sound can cover about 18000 sq.ft (1800 ), loud enough for a very big room or a wide outdoor area. Built in 2000 mAh high capacity rechargeable lithium battery. Continously working time is up to 18 hours, which can meet full day use. Only needs 3~5 hours to fully charge it. Compact size (3.9 x 1.7 x 3.5 inches) and light weight (0.49 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. Supports MP3 audio playing: TF (Micro SD) card playing & USB flash drive playing. Can repeat single tune, loop all music and switch songs. Supporting 3.5mm AUX audio input, can work as a wired speaker. The wired headworn microphone is adjustable. You can adjust the distance between your mouth and the mic. Made of durable and wear-resistant ABS material, this voice amplifier looks fashion. Suitable for teaching, trainer, singer, coacher, tour guide, shopping mall, presentation, outdoor speech and etc..