I have the Fitbit One, but I no longer use it. It measures steps well and I like the number about the flights of stairs climbed, but I also do a lot of things that it cannot measure. I use the stationary bike at the Y. I swim and do a water aerobics class, so my numbers on those days was an inaccurate measure of my activity. I hike a lot and steps on a hiking trail are not always the same length as my steps when I walk in my neighborhood, so the steps were correct but the mileage was very inaccurate. And the calorie count never made sense. It was fun at first, then became something else I had to keep charged.