I used a single diode cold laser in the 800-900nm range. I don't know if the below resource will provide you with someone who has that type. It can also be 2-4 diodes. I would treat the nail and the nail bed on each visit. Cold lasers in the 600nm range are the same as laser pointers that you can buy at an office supply store. I don't recommend these, although they might have some effect. If you buy Bowtrol, look on E-Bay first for a bargain. Mid American Marketing, 1-800-922-1744, may also be a good source.