I should say that I am not a doctor. It gives me about the same readings as the watch GT4/GT2. No, it is not a professional tool, but 2 different devices give me the same reading (sounds pretty good). Also, once it gave me a reading below 90 and I went to my son at the hospital, it saved us.

Wrong measurements of oxygen and pulse. Oxygen measurements constantly below 92 and pulse measurements constantly at 89-90. If I didn't compare it with the doctor's, I would remain worried that I have a problem!

I bought it from my neighborhood pharmacy, supposed to be a good and quality oximeter, they say it's German with warranty. I paid 40 euros, but when it measures, it shows 70, sometimes 90, and even 55. I wasted my money, and I also read at least two other reviews with the same issue... so it's not just a coincidence. Not to mention that when I got it, I mentioned it to my mother-in-law who has a Chinese one, and in the end, I even lend it to her

I had borrowed it in the past, that's why I bought it. Completely satisfied! I haven't checked oxygen measurements, but heart rate matches the blood pressure monitor. There may be cheaper options, but I don't know if it's worth it to invest in such tools.

The oximeter is excellent in terms of quality. I have used some Chinese ones and of course, this one is much superior in terms of quality. Now, as for the measurements, the truth is that at first, I was ready to throw it out the window (okay, I would have returned it). It takes a little time to stabilize because while it starts, for example, at 97 in oxygen saturation, it then decreases a bit before going back up and stabilizing at 98. It is not as fast in delivering results as some others, but at least that's what I observed with mine. And it has great accuracy in measuring pulse rate.

Unacceptable... the measurements are laughable...
From 55 oxygen to 99...
Pulses from 35 to 122!!!
I spoke with the company I bought it from and then someone from the dealership called me...
I explained what was happening and he seemed surprised... because he considers it very reliable... I sent it with a courier to examine it and call me...
Great inconvenience... I paid 45 euros and I don't have an oximeter...
I tried some other oximeters of my friends, Chinese ones and one bought from the flea market, much cheaper but they show very accurately...
My German one with a 5-year warranty is a waste... such a shame...
I will inform you again as soon as I have updates.

Unacceptable for its price.
I am referring, of course, only to my own and my own experience.
Unfortunately, its measurements are all over the place.
I have had it for 15 days and the oxygen readings range from 99 to 60, and the pulse readings range from 80 to 30.
I change fingers and hands, but it is completely unreliable as you never know in which phase it will give you accurate measurements. It does the same with my wife, inconsistent numbers.
Compared to a reliable Chinese one that I have and has been evaluated medically, it has no relation.
I spoke with the company from which I purchased it, I will return it and inform them about the outcome.

The oximeter is excellent, I compared it with a professional one simultaneously and the measurements were the same! It's worth it!

Very satisfied with the purchase. Reliable measurements for both me and my wife. It simultaneously measures oxygen saturation and heart rate with a graph for the pulses. It comes with a strap, a carrying case, and batteries included in the package.

Excellent and reliable oximeter. Great accuracy in oxygen measurements and heart rate pulses while also displaying its function (something like an electrocardiogram).

It is a reliable oximeter that I believe is worth its money. I have compared its measurements with another more expensive one from the same company and there is no deviation. Personally, I am satisfied with this purchase.

I do not belong to the medical personnel, so I have no way to verify the accuracy of oxygen saturation with a medical-grade oximeter. It was purchased for reliable measurement of both pulse and oxygen. Its construction is very high quality and its indications as well. The pulse is displayed in the form of a cardiogram, which, although it appears as an effect, actually detects some basic waveform and in any case enhances the reliability of the heart rate at least. The screen is reversed depending on the position it is in, which is useful in case you measure on different fingers and hands to ensure the accuracy of the measurements statistically.
Its price is approximately the same as the PO 30 (42 €), and it includes a lanyard to hang around the neck as well as a black canvas case. Two AA batteries are included.
Overall, absolutely satisfied.