The Dynatron 925 5 Channel Combo Stim Ultrasound unit offers 1, 2, and 3 MHz frequencies for the greatest flexibility in depth of treatment. Choose 1 MHz for deep treatments, 2 MHz for moderate depth, or 3 MHz for superficial depth. All channels allow fully-independent treatment setups as well as ComboPlus technology offering Ultrasound in combination with Interferential, Premodulated, Biphasic, High Voltage pulsed stimulation, and Russian stimulation using any available electrotherapy channel.