The US 111 device is a portable, therapeutic ultrasound device that produces deep heat (you don't even sense) in your tissues and muscles, through its crystal sound head.Ultrasound has a long history of therapeutic use by pain management professionals, physiotherapist & sport medicine professionals. And the safety & effectiveness of ultrasound as a pain relief modality has been scientifically proven. Now, technological advancement has made ultrasound machines available for home use.