My Huawei GT2e measures oxygenation with better precision than the finger apparatus I also have, when tested against hospital equipment, so one would hope Apple isn't worse than a watch half the price.My series 4 SS still looks and works great. AOD would be great for swimming but I'll wait for the 7. Pulse ox is not something I would be checking regularly and if I did I would just get a finger sensor for £20 which probably would work better anyway. I do like SBSS so I hope that is coming back