1) Excellent product, especially for its price of 230 euros.
2) Attention, the same product is available from other companies with or without its specific sensor, which is small and does not bother at all. It also has Velcro straps for additional support and is precise on all fingers, even the small one.
3) You need to use the codes inside the package to download and activate the software from the special website.
4) The software is quite good, but the manual is written by "doctors" and you may need technical guidance.
5) Do not let the battery completely discharge, as the data will be lost.
6) It records and simultaneously provides audio warnings when the pulse and/or oxygen fall below or rise above the limits you set based on your personal needs.
7) For an additional 500 euros, there is a "competitive" product with mini alkaline batteries that, unlike the rechargeable nickel, does not limit you to 12-14 hours of continuous monitoring. For another 250 euros on top of the 500, it also has WiFi for data transfer without disconnecting the sensor.
8) Its sensitivity and accuracy are proven to be excellent, on par with professional devices costing 1000 euros. I compared it myself when I did a sleep study and they measured my oxygen with blood analysis and a professional oximeter. It also never loses the heart rate rhythm like many other oximeters do in people with frequent cardiac arrhythmias.