On Wednesday, September 16, 2020 at 8:30:05 AM UTC-6, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Walt,

Agreed generally with two comments;

1) I would prefer a watch that I can glance at randomly than something I have to clip on from time to time.

2) The cheap OLED fingertip models are very hard to read in direct sunlight. The LCD versions are MUCH better in this regard but harder to find.

- John

Slip the pulse oximeter on a thumb, press the button, wait a few seconds. Then curl the other fingers on the same hand over the thumb and device to shade the display, assuming your dexterity allows that. Look at it just below those dark sunglasses. Even an OLED display is readable when direct sunlight and sunglasses are not in the way. Then a sub-$20 pulse oximeter is the cockpit instrument with the best return on investment, especially for high altitude flights.