Conventional TENS
(Local Relief)  This is the most proven mode of TENS and is usually most effective for relief of "local" moderate to superficial myofacial type pain.
Modulation -(SAM) Simultaneous Asynchromous Modulation
(Local relief) This is an asynchromous (out-of-sync) combination of rate and width modulation.  This is a variation of conventional TENS, which may offer a "subjective" variation in sensation.
BURST
(Systemic relief)  Burst TENS is a variation of low rate TENS with a more comfortable delivery of "bursts" of low frequency versus "beats" of low frequency.  This method appears to be more acceptable for patient compliance.  Low rate types of TENS might improve efficacy on deep diffuse types of pain.  It may increase endorphins in the cerebral spinal fluid.

Pulse Amplitude
Adjustable, 80 mA peak maximum for positive pulse or -20 mA maximum for negative pulse into 500 ohm load each channel.
Channel
Dual.
Pulse Rate
Adjustable-  2 Hz to 120 Hz.
Pulse Width
Adjustable-  40 uS to 260 uS.
Burst Mode
Bursts consist of 9 +/- 2 pulses at maximum pulse rate.  Bursts occur twice every second..
Modulation Mode
Pulse width is automatically varied in a cyclic pattern over an interval of nominally 5.0 seconds maximum.  Pulse width decreases linearly over a period of 1.5 seconds from the control setting value to a value which is decreased 45% maximum.  The narrower pulse width will continue for 2 seconds maximum, then increase linearly over a 1.5 second period to its original value.
Wave Form
Asymmetrical Bi-Phasic Square Pulse.