Targeted training made easy with digitally coded monitors to ensure training data is recorded accurately and available for detailed analysis. All Onyx models include ECG-precise heart rate tracking, water resistant cases, backlight, tool-free battery compartment. Fit model includes setting based upon maximum heart rate or individual anaerobic threshold (IAT). Fit model also includes the VO2 max Rockport test. Balance model features easy-to-read extra-large figures (same computer, different colors).