Lifespan Fitness Heart Rate Monitor Ring (Monitors: Heart Rate, Time, & Stop Watch) - Choose Your Color! One size fits all design also includes silicone finger insert to accommodate and fit fingers of all sizes Clock, Stopwatch and Heart Rate are the rings readouts Easy to use 2 button design Great alternative to the cumbersome heart rate strap and watch sets Measures heart rate from 30 - 250 beats per minute for efficient monitoring of your workout progress