Amrex Portable Ultrasound Unit U-20. The widely used therapeutic modality of ultrasonic diathermy is provided by the SynchroSonic U/50.The Amrex U/20 Ultrasound Unit is a portable, low-power ultrasound therapy solution. Unlike diagnostic ultrasounds, this therapeutic ultrasound device runs at a low frequency rate, making it a noninvasive alternative for treating a variety of subdermal ailments including bursitis, tendinitis, and various sprains and ligament injuries. Relying on vibrating soundwaves, the U/20 Ultrasound Unit dilates microvessels to increase blood flow. Like a heating pack or massage, though with greater concentration, this ultrasonic therapeutic approach aids in the repair of damaged tissue.