Red light occurs within the visible light spectrum. Although it does not penetrate as deep as near infrared, red light seems to help wounds heal more quickly. At a wavelength of 660nm, it penetrates tissue to a depth of 8-10mm and is beneficial in the treatment of problems close to the surface of the skin such as acne, wounds, cuts, and scars, and is particularly effective in treating infections. It can also be used to remove precancerous skin cells without scarring.