Our Brief Summary
Forerunner 305 includes a heart rate monitor and can also work with an optional cadence sensor.
Forerunner 205 & 305 are newer than Forerunner 101/201/301. They have a redesigned case, more sensitive GPS reception, and updated functionality (including a new courses feature).
Here's a link to more product information on FR305 at Garmin's web site.
Reviews & Comparisons