Usage Tips:Small but very powerful: : If you want to buy a small and light personal voice amplifier, then the S17 is for you. This is a portable microphone speaker with 30 watts output power, which can greatly amplify your voice and protect your vocal cords, so that you can easily make your voice heard. voice per 25-100 people. Battery Life: -- The small voice amplifier comes with a high capacity 2200mAh rechargeable Li-ion battery that provides up to 12 hours of operation on a fully charged battery. Charging is easy with a supplied USB cable. And it only takes 3-5 hours to be fully charged. Convenient and Portable: -- The portable speaker comes with an adjustable strap that can be tied around your waist or hung around of your neck. The teacher speaker amplifier has a clip on the back, you can clip it to your belt or waist. The microphone of the wired headset is adjustable. Stable performance: : This is an voice amplifier with stable performance. The portable headset microphone has a flexible gooseneck design that sits right next to the mouth. Ideal for anyone hosting events and needing to project their voice. Suitable for teaching, coach, singer, trainer, tour guide, shopping mall, presentation, yoga, outdoor speech, etc. Size: 8, 4 x 9.2 x 2.8cm