1. Small But Very Powerful -- If you are looking to purchase a personal voice amplifier that is small in size and lightweight, then S17 is right up your alley. It is a portable microphone speaker with 30 watts output power, which can clearly amplify your voice and protect your vocal cords, allowing you to easily make your voice heard by 25 to 100 people. 2. Long Battery Life -- The small voice amplifier has a 2200mAh rechargeable Lithium Ion battery that provides up to 12 hours of operation from a fully charged battery. Charging is simple via a USB cable that is included. And it only takes 3-5 hours to fully charge. 3. Comfortable and Portable -- Portable loudspeaker comes with an adjustable band that you can use it to tie around your waist or hang on your neck. Teacher speaker amplifier has a clip on the back, you can clip on a belt or the pant waistband. The wired headset microphone is adjustable. 4. Stable Performance -- It is a voice amplifier with stable performance. The portable headset microphone is a flexible goose neck design that directly positioned near your mouth. Great for anyone who does events and needs to project their voice. Suitable for teaching, trainer, singer, coach, tour guide, shopping mall, presentation, Yoga, outdoor speech and etc. 5. Size: 8.4*9.2*2.8CM