The company i bought the ultrasound from is......tenspros. FYI.....several yrs ago, i bought one, and it was $150...........i took it to my naturopath Dr., and she said i chose a good unit. but, a few weeks ago, i decided to give mine to my grandson, and buy a new one....hmm........their website had one, same name, for $49. And one for $149......I did that sorry thing and "assummed" the 149 one must be a newer version, or something. they are the same. so if you check out their website, and see the same thing, you might want to e mail, or call them and ask what is the difference......maybe, the cheaper one is refurbished????.........altho i haven't found much info on how to use one, i did read you should only use it 2 or 3 times a week. I just got in my Dr Ho' s unit , a tens unit, but this one you place your feet on their foot pads, instead of putting a couple of electrodes on them. so far, i sort of like that, because i can feel the sensations shooting up my leg, up to the knee. I e mailed the company for a little info, and they said to use it aprx 20 mins 2 to 3 times a day. i've only used it twice so far. Hope we both find some thng that will work for us.