Bests & Worsts Reviews from Amazon

So I actually have 4 heart rate monitors, I have the Polar H7 HRM, the Samsung Icon X (w/HRM), Atlas fitness watch (w/HRM) and a fitbit Charge 2 (w/HRM). I know, it's over kill, but what better way to determine if your devices are accurate or not then to compare them with other HRM's at the same time? Well I took all 4 to the gym today and I hit the cardio machine and exercised for 60 minutes and set each device to log my HRM in their respective apps. Throughout my workout, the Polar, Samsung and the Atlas fitness watches were all within +- 2 heart beats from each other (150-165 beats) while the fitbit hung in there for about the first 15 minutes of the workout then after that the display was showing my heart rate at least 30 beats behind the others then after about 30 minutes my heart rate on the fitbit was a good 80 heart beats behind then shortly after that it stopped measuring my heart rate completely, Off and on and it would show a heart rate through out the remaining workout, but it was showing it only in the 50-70 range while the other 3 devices were showing my heart rate in the 155-160 range. Chest HRM's are supposed to be one of the more accurate ways to measure your heart rate when exercising and seeing that 3 of the 4 HRM's I had were all within a couple heart beats from each other makes me believe the Polar (and the Samsung and Atlas) are fairly accurate in their readings. The fitbit, well, if it wasn't for the auto sleep profiling, that one would be going back to the store since it doesn't seem to be very accurate for it's intended purpose, being a fitness watch. All in all, i'm very pleased with the Polar H7 HRM and I'll continue to use that for my cardio exercises and I'll rely on the atlas and Samsung when i'm doing weight exercises since wearing a strap is a bit annoying to me when i'm lifting weights. The fitbit... well... if I don't return it, it'll just be relegated to being a sleep monitor and that's it as I don't trust it for measuring anything else.