Contec CMS-50F -- what is up with the probe?!

I tried to wear the Contec CMS-50F and the probe is gigantic and bumps the sheets and feels like it's going to get dislodged. On top of that, after an hour and a half of not sleeping with it (only partly the oximeter's fault, perhaps), my finger was killing me! The probe looks soft, so I don't know what the deal was... I tried it on my index finger and it couldn't reliably keep a signal, so I wore it on my middle finger. Still doesn't seem like it should have been that uncomfortable. Am I doing something wrong?!

Also, sometimes I can't get a reading from it, and other times it reports an oxygen saturation that is too low to be right (my oxygen saturation can't be between 80 and 90% when I am awake if at worst it's 92 or 93% while asleep without CPAP, per sleep study!). Is something wrong with the one I got?

I have the the CMS50F and have had no problems with it. I believe your supposed to put it on your middle finger, and it goes on one way with the cord staying on the top. There does seem to be a little excess cord from the watch part to the probe, but I find it comfortable enough, not too tight or loose, but my fingers are pretty big. Your saturation level does sound screwed up, mine pretty much stays in the 90's while awake, and asleep. Maybe your getting those funny readings if your finger is not all the way in to the end? The only problem I have had has been a low 02 spike which set the alarm off if I move too quick in my sleep, but it only happens for a second or so. I think I remember another person here having extremely low 02 readings, maybe there are some bad ones out there.

The probe is long for me. Sometimes I wear the monitor on the inside of my wrist and loop the wire across my palm and around the back of my hand to take up the slack so it doesn't catch on the blankets.
Lately I've been slipping the wristband over my fingers with the screen inside my hand and upside down, and then attaching the probe to a finger. This is so I can press the button to read the screen with out reaching over with the other hand. Sounds nuts but it's difficult to do when you're sleeping on your stomach.
That's the only thing I do like about the fingertip model is that you can press the button with an adjacent finger to read it.

Yes the probe is weirdly wide but it doesn't hurt my middle finger. It takes a minute or so for it to "settle in" to give an accurate recording. Do you move a lot at night?

I have generally been happy with mine but had to return a couple because the oximeter lost contact with the probe. I like the unit itself but feel they have some problems with quality control.

I have considered carefully trimming/shaving down the sides of the probe, but haven't done it yet.