Bests & Worsts Reviews from Amazon

I bought an SM-110 three years ago. I checked the accuracy by against ones used at the hospital and it was dead on. I gave my unit to my mother recently and ordered another one just like it on Amazon. It came promptly but it was reading the oxygen level lower than the one I gave my mother. I called Gurin Products LLC in Santa Ana CA. , they were the ones who shipped it to me. I explained my problem and the shipped me another one at no cost and it arrived the next day. This is a great company to do business with and the SantaMedical Deluxe SM-110 is a good product. I would recommend it to anyone needing one. Gil Johnson