Noise Indicator NI-100 is designed to alert users to hazardous noise levels, helping identify areas where hearing protection may be needed. Users clip the Noise Indicator to a shirt or jacket, and its LED light provides a clear indication when noise levels exceed a potentially hazardous threshold. The NI-100's small size and lightweight design make it ideal for workers in a variety of industries. With a rechargeable battery that operates for up to 200 hours between charges, itâ€™s an economical investment in your hearing conservation program. A mini-USB cable (sold separately) plugs into bottom port of device to recharge.