Smart LED Battery Display Allowing you to monitor usage in real-time. Avoid interruptions during important lectures or presentations with this convenient battery indicator. 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. Support TF Card Playing Provides reliable and flexible audio connections. Powerful Sound This classroom microphone has up to 8W output crystal sound and no noise, the sound of microphone headset for speaking is loud enough to cover a large room of 25-100 people. 2200mAh Voice Amplifier Rechargeable Built-in a 2200mAhlarge lithium battery allows the teacher microphone for classroom 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. Multifunctional Personal Voice Amp This portable microphone headset with speaker supportsMP3 audio playing: TF (Micro SD) card playing & USB flash drive playing. Voice amplifier with microphone headset can repeat single tune, loop all music and switch songs. Comes with Head Speaker and Adjustable Waistband You can easily adjust the distance between the microphone and your mouth with its flexible gooseneck. This personal microphone for teachers comes with an adjustable band that you can use it to tie around your waist or hang on your neck. Specifications: Output Power: Up to 8W Charging Time: 4-6 hours Amplify Time: Up to 20 hours MP3 Music Playtime: Up to 13hours Battery: 2200mAh lithium batteries Charging Voltage: USB/DC5V1A Loudspeaker:3 inches 2 ohmic magnetic speaker Jack Size: 3.5mm Size: 3.6 x 2.8 x1 inches Net Weight: 0.4lb Package Included: Voice amplifier*1 3.5mm headset microphone*1 USB charging cable*1 User manual*1 Waistband*1