Bests & Worsts Reviews from Amazon

I purchased this product for my husband coming home from the hospital. As we get older it seems we need these helpful items to know how our health is going. I like the fact that this one is small and easy to use; but confusing as to being able to read it. Assume I would put it on my finger and basically look at my numbers with it upside down (meaning the "on" button is at the bottom when reading it.) This seems unnatural; but it is easy to use. I have not checked it with my doctors oxygen meter yet.