If you're an athlete looking for training guidance, you'll get everything you need with the S-210. You can program the watch to store the training parameters (TZ, timers, recovery) of your five most popular workouts. Just select the workout on the watch, put the transmitter on, and get going. the S-210 will coach you through your workouts. Functions: OwnIndexSTM - Measures your VO2 max, OwnCalSTM - Tracks energy expenditure, OwnCodeTM - Personal transmission feature, Exercise SetTM - program the parameters of five key workouts (TZs, Timers, Recovery), maximum heart rate, view heart rate as a % of Max hr, average and recovery HR, new ultra-thin chest transmitter, 3 target zones w/ alarms, 3 countdown timers, 5 setting for key exercise workouts, interval function, lap splits w/average HR, time in, above, below target zone, low battery indicator on watch receiver, easy to use programming logic. Also functions as a stopwatch and an everyday watch.