The basic T-Zone LED Device uses white LEDs with cover colours. There are three replacement LED plates available for the device. The plate LEDs use the wavelength, 470nm, 660nm or 880nm. LED Device sold separately.
660nm appears as red light
Visible red light at a wavelength of 660nm penetrates tissue to a depth of about 8-10 mm, which means it’s very beneficial in treating issues close to the surface of the skin.
Recent studies have shown the efficacy of 660nm (red) and 880nm (infrared) LED light in the management of sports and muscle injuries.
The red light can be used for 24-36 minutes, 2-3 times per week.
References
Healing with single-frequency light:
http://www.consumerhealth.org/articles/display.cfm?ID=20000102232338
Light Emitting Diodes Bring Relief to Young Cancer Patients:
http://www.nasa.gov/vision/earth/technologies/led_treatment.html