I've got this cheap one from China. Cheap and effective. Others will not agree that it is effective. They are wrong. And IF it breaks... just buy a new one. Ten times cheaper than a "good" one, but just as effective in my experience. I've been using the same one for like 5 years, it still works fine. Needs to be calibrated with every use, but so what. Take care of it, and it will take care of you.