【Small Size and Powerful Sound】The personal voice amplifier is mini in size and light in weight (size 3.6 x 2.8 x 1 inches and weight 0.4 lb), but with up to 8W output crystal sound and no noise. the sound of microphone speaker is loud enough to cover a large room of 25-100 people. The stable performance perfect for amplifying your voice and saving your throat. A best portable amplifier for teaching, trainer, singer, coacher, tour guide, shopping mall, presentation, outdoor speech and etc.【Multifunctional Teacher Microphone】This microphone for classroom teachers supports MP3 audio playing: TF (Micro SD) card playing & USB flash drive playing. Portable microphone headset can repeat single tune, loop all music and switch songs. The portable microphone and speaker has 3.5mm jack,, can work as a wired speaker.【2200mAh Rechargeable Voice Amplifier】Mini voice amplifier has a built-in a 2200mAh large lithium battery, that allows the portable speaker with microphone to take 4-6 hours to fully charge, but plays up to 20 hours of amplify time and up to 13 hours of music playtime.【Comfortable and Portable Mic】①The head microphone is lightweight and adjustable. You can adjust the distance between the microphone and mouth with its flexible gooseneck. ②This microphone headset with speaker comes with an adjustable band that you can use it to tie around your waist or hang on your neck. ③The headset microphone for speaking has a clip on the back, you can clip on a belt or the pant waistband.【Warm Tips 】Please charge the classroom microphone for teachers before first time using, keep the voice microphone and mic for a distance to avoid the noise.