"BioStim SD Digital TENS. It is a compact, extremely durable and portable unit measuring 3.9"" x 2.5"" x 1.1"" and weighs only 3.25 oz. The unit outputs an asymmetrical biphasic square waveform and includes adjustable pulse width (10-250US) and frequency settings (1-200Hz). The device can be turned up to 98mA to accommodate even the most high-demand patients. The device has large, easy to press buttons and no small dials, enabling ease of use by patients with dexterity issues. The lead wires are durable and easy to handle and install. The device closes, covering all of the controls to prevent any accidental changes during use for added safety. The large 1.5"" x 1.75"" display is easy to read. The belt clip is made of a durable polymer plastic and can be easily removed and replaced by the patient if necessary. The device automatically detects when the batteries are running low and a battery indicator light on the screen flashes, notifying the patient that the batteries should b