Hisonic HS161 is desgined as a compact personal voice amplification system for people with low-volume speech (very soft speaking voices or esophageal speech). It is extremely useful for people with Parkinson"s, MS and other conditions that cause a strain on the larynx. This is also ideal for professionals who place heavy demands on their voices, including teachers, tour guides, trainers and trade show presenters. This system can give you 20 decibels of voice boost. Its operating time on a full charge is between 6 to 8 hours depending on the volume setting. If the batteries runs low, you can simply connect this unit with the AC/DC adapter, and plug the adapter into a wall outlet for a few hours, then you are ready to go again. Unlike some other systems that use AA batteries, this one has a built-in Li-ion 1,000 mAH rechargeable battery with longer lifetime and more charging cycles. It can also be easily replaced when the battery can"t hold the charge any more.This system comes with a headset microphone with an adjustable boom so that the microphone can be positioned very close to your mouth for the best amplification with the least vocal effort. Weighing a little less than 2 lbs. (with batteries), The HS161 offers you maximum physical comfort and discreet wearing and allows you independence and ease of communication with everyone anywhere you go.If you need to find out more about this product, you can reach us toll free 866-524-8676, M-F, 9AM-5:30PM Pacific standard time, excluding major national holidays.