Here at New Jersey Wellness, we take pride is using the SIGMA Ultralign instrument for our patients. The SIGMA Instrument virtually puts all the fears of manual treatment to rest. The Ultralign utilizes a precise oscillating force with uninterrupted motion. It is able to increase mobility of the spinal segments by reducing or eliminating the fixations. It uses soft tips, that are comfortable to the human body to exert a tapping force that “unsticks” the joint.
Source: http://www.sigmamethods.com/pub_about_sig_instruments.php