Four Channel System * Our most popular units they both offer the convenience of a full-featured Stimulator and Ultrasound in one unit * 4 Waveforms (Interferential Premodulated High Volt and Russian) * Ultrasound features include 1 and 3.3 MHz frequencies 10% 20% 50% and Continuous Duty Cycle selections with Head Warming * Bright back-lit LCD display * Optional 2cm2 and 10cm2 soundheads * Includes Nylatex