Bests & Worsts Reviews from Amazon

I bought this pulse-oximeter after seeing articles about how some victims of COVID-19 can present with significantly diminished oxygen saturation of the blood while still feeling relatively OK, which is an effect that seems to be peculiar to COVID-19. The suggestion was that it might be preferable to begin to treat virus-positive people when their oxygen saturation dips below 90%, rather than wait until it crashes vastly lower, which apparently frequently happens, and which at that point is a crisis situation that may be difficult to reverse. Should the worst happen, and I become infected and began to experience symptoms at home, this device will provide useful data to share by email with my PCP as he considers what to recommend. The device worked right out of the box. The only negative I have to report is that the cover seemed scuffed and scratched (see first photo) as though this was not a brand new item. However, it turns out that the marks are on a removable film, and once that was taken off, the device seemed pristine. It is kind of annoying that the film, and the need to remove it, doesn't seem to be anywhere in the product materials. I installed the batteries according to the standard "+/-" labeling. I pushed the "on" button and the lights went on. I put my index finger into the device, waited a few seconds for it to calibrate, and bang - there was my pulse (65) and my oxygen saturation (97), just like that. Over the following several days, I've checked several times a day, and my pulse is ranging from the mid sixties to the mid eighties, which is pretty consistent with the values measured when I go to the doctor. My oxygen saturation levels range from 94 to 99%. Technically I did not feel I could give a rating for "accuracy" for this product, since I don't have an independent way of checking its values, but obviously I am getting readings consistent with a healthy person, so it seems reasonably accurate. Some reviewers have raised the issue that, when the hand and fingers are extended in the standard manner for taking a pulse-oximeter reading, the values are presented in such a way as to be upside down to the person being tested (see middle photo, hand with outstretched fingers). And, in fact, some competing devices do seem to have the ability to "flip" the values for easier reading. However, I didn't really have a great deal of difficulty in flipping the values in my head. In addition, I discovered that my wrist is flexible enough that I can turn my hand and bend my index finger and read the values "right side up" (see third photo). While one might be concerned that this maneuver might constrict blood vessels and compromise the reading, I found that the reading was exactly the same either way, as shown, and was stable if I kept my hand in this position. So I really don't see that this orientation issue should be a big factor in deciding whether to buy this item. In spite of slight misgivings about the "upside-down" issue and some reports of the device not working on arrival, I took a chance on this particular manufacturer because there were many reviews, stretching back to pre-COVID days, and that made me comfortable. The company seems to be implying, without saying it directly, that at least some reports of the device not working might be ascribed to improper insertion of the batteries. In addition, as described above, I don't see the "upside down" orientation of the data to be a significant issue. I'm glad I took a chance. The device worked immediately, and it has continued to work over the last week.