Small Size and Powerful SoundThe 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 MicrophoneThis 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 AmplifierMini 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 MicThe head microphone is lightweight and adjustable. You can adjust the distance between the microphone and mouth with its flexible gooseneck. This microphone headset with speaker comes with an adjustable band that you can use it to tie around your waist or hang on your neck. The 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.