I have had it at my disposal for 1.5 months. Little time for evaluation, however, I have not noticed any malfunction. ............... It has been a satisfactory amount of time now and I can say that it functions satisfactorily without any problem.

Negatives: Chinese. Same as much cheaper ones. For example, same software, same sensor, same measurements, same manufacturer as an oximeter from a supermarket chain with weekly offers (14.99€).
Positive: It works normally. Measurements 3-4 times a week.

Excellent with a clear screen and extremely reliable with very good build quality. I checked it for accuracy with our family doctor's oximeter and there is no deviation. The batteries last for a very long time. Highly recommended.