No GPS calibration is needed and it offers 99 percent distance accuracy in environments with a clear view of the sky. Speed and Distance features include tracking of your workout distance (with target distance alerts), continuous odometer for total distance for a workout or group of workouts, and a predictive finish time mode that uses total event distance and pace data. The heart rate monitor features include:

• Target Zones: Preset your desired heart rate exercise zone. Alarm notification when you are not in zone.
• Average Heart Rate: Displays your average heart rate over a period of time.
• Time In Zone: Amount of time spent within your selected heart rate target zone.
• Four Linked Interval Timers: Program up to four linked timers each interval with its own target zone.
• Recovery Heart Rate Timer: Measure your heart rate after a timed recovery.
• Max Heart Rate Zone Calculation: Automatically sets your five training zones; one manual zone.
• Digital Transmission: Timex's system protects your data from other heart rate monitors and most exercise equipment.
• Automatically sets your five training zones; three manual zone settings.

• 3-line customizable display
• Summary Mode: review navigational, speed, distance and heart rate performance data at end of workout
• 100-hour chronograph with either lap/split in large digits,
• 100-lap memory with recall of Bodylink system data
• 2 linked interval timers
• 100-hour, 3-mode countdown timer
• 5 alarms for daily, weekday, weekend or weekly with 5-minute backup
• Up to 2 year battery life
• Included bike mount

The Indiglo night-light uniformly lights the surface of the watch dial using patented blue electroluminescent lighting technology. It uses less battery power than most other watch illumination systems, enabling your watch battery to last longer. The Night Mode feature allows you to illuminate the Indiglo night-light for 3 seconds with any button press, regardless of the mode or function. The watch is water resistant to 50 meters (165 feet)--suitable for swimming but not for diving--and the GPS sensor is splash resistant. All Timex heart rate monitor sensors have batteries that can be replaced by consumers without requiring them to be returned to the manufacturer.