The Garmin Forerunner 305 GPS unit with heart rate monitor. You can keep tabs on how hard you're working, making sure to neither over or under exert yourself. (Photo by Walter Cruz/Dallas
15 Years This Week: The Forerunner 305 Was Released: How does it test now? | DC Rainmaker
Amazon.com: Garmin Forerunner 305 GPS Receiver With Heart Rate Monitor (Discontinued by Manufacturer) : Garmin: Electronics