I've been using this product for 3 weeks. Works very good and seems to be accurate. At this time in Canada I usually have 3 layers of clothing on when using this HRM outdoors with no problems communicating with my iPhone 4S. I've compared it while on the Precor treadmill HRM and ellipticalHRM and was usually within a couple of beats of each other. Setup on WahooFitness, Runkeeper and iMapMyFitness apps was a breeze . All paired up immediately with no problems. I'm using it mostly with the Runkeeper app.