Dpl therapy led light treatment pain relief system is for the treatment of pain, relief of muscle and joint aches, sprains, back pain and the pain and stiffness associated with arthritis. the dpl system uses a form of energy called photons to penetrate deep into the body easing pain and repairing damaged tissues. the dpl therapy system is a non-invasive, drug free therapy which can be applied to your specific and individual needs. light therapy has been shown in over 40 years of independent research worldwide to deliver powerful therapeutic benefits to living tissues and organisms. both visible red and infrared light have been shown to affect at least 24 different positive changes at a cellular level. visible red light at a wavelength of 660nm penetrates tissue to a depth of about 8-10 mm. it is very beneficial in treating problems close to the surface of the skin such as wounds, cuts, scars, and treating infection. infrared light at 880nm penetrates to a depth of about 30-40 mm which makes it more effective for bones, joints and deep muscle problems.