It seemed pretty simple to use. Like all Pulse Oximeters, you just need to place your finger inside. I found it to be very testy about how far my finger was pushed into place. Unless I had it pressed very firmly against the back, it would not register my finger and would just shut off instantly. After getting the hang of placing my finger just right, the device worked satisfactorily.
I compared the readings of both the SM-150 and my more expensive Pulse Ox, and the readings were pretty much the same. As far as accuracy, it's pretty good, especially for it's value. The display is large, bright, and easy to interpret. I give this 4 out of 5 stars, and would recommend it.
I purchased this pulse oximeter at a discount in exchange for my honest and unbiased opinion.
Grab one on Amazon.
~Crystal Vicious