Explanation Compact But Powerful - If you want to buy a compact and lightweight personal voice amplifier; s17 is tailor-made for you. This is a portable speaker microphone 30w output power greatly amplifies your voice and protects your vocal cords so you can easily get your voice heard by 25-100 people The small voice amplifier is equipped with a large capacity 2200mah rechargeable lithium-ion battery which can work for 12 hours on a fully charged battery. Recharge easily with the included USB cable. Charges in 3 - 5 hours easy to carry The portable speakers have adjustable straps that can be tied at the waist or hung on the neck. The teacher speaker amplifier has a clip on the back that can be attached to the belt or belt. Adjustable wired earphone microphone stable performance - This is an original voice amplifier with stable performance. The portable mini helmet is a flexible swan collar located on the mouth. It is ideal for all organizations and people who need to project sounds. It is applicable Teaching; coaches; singers; trainers; tour guides; shopping malls; conferences; yoga; outdoor presentations; etc. dimensions: 8.4 x 9.2 x 2.8 cm