It took me awhile to figure out what finger to use and the best spot to attach it to. In result, the most accurate reading I get is when I attach it to the tip of my middle finger or thumb. Overall, it is more comfortable fit for me for the overnight wear when I use my middle finger with device taped for extra security so it doesn't come off when I move in my sleep.I find this device more ACCURATE than some other brands that I have tried, battery life is plenty, it FITS GREAT for overnight wear with some taping, the ALARM function is simply AWESOME and the main reason I bought it in the first place (I had afib event w. a trip to the hosp recently due to hypoxemia... now I am reminded to breath at night now and then).Personally, I am going with the extended 3y warranty as some people complained about device quality, which probably makes sense if it is used daily.