DNA resonate the most in the 600nm range. 600nm range is also best for muscle repair and bio-stimulation IMHO. Most lasers in that range are either 635nm,650nm, or 660nm (660nm is less expensive because it costs less to manufacture and is dimmer but will still work). I had one custom made to my specs (635nm with a line generating lens) so you can sweep across a large muscle group at once.