Physical & Performance:

Unit dimensions, WxHxD: 2.1" x 2.7" x 0.7" (5.33 x 6.86 x 1.78 cm)
Display size, WxH: 1.3" x 0.8" (3.3 x 2.0 cm)
Display resolution, WxH: 160 x 100 pixels
Weight: 2.72 oz (77 g)
Battery: rechargeable lithium-ion
Battery life: 10 hours, typical
Waterproof: yes (IPX7)
GPS-enabled: yes
High-sensitivity receiver: yes
RoHS version available: yes

Maps & Memory:

Basemap: no
Ability to add maps: no
Accepts data cards: no
Lap history: 1000 laps
Waypoints/favorites/locations: 100
Routes: 50

Features:

Heart rate monitor: yes
Bike speed/cadence sensor: no
Foot pod: no
Automatic sync (automatically transfers workouts to your computer): no
Garmin Connect™ compatible (online community where you analyze, categorize and share data): yes
Garmin Training Center™ software compatible: yes
Virtual Partner® (train against a digital person): yes
Courses (compete against previous workouts): yes
Auto Pause® (pauses and resumes timer based on speed): yes
Auto Lap® (automatically starts a new lap): yes
Auto Scroll (cycles through data pages during
workout): yes
Multi-sport (automatically changes sport mode with a press of a button): yes
Advanced workouts (create custom, goal-oriented workouts): yes
Quick workouts (input time, distance and pace goals): yes
Pace alert (triggers alarm if you vary from preset pace): yes
Time/distance alert (triggers alarm when you reach goal): yes
Interval training (set up exercise and rest intervals): yes
Customizable screen(s): yes
Barometric altimeter: no
Unit-to-unit transfer (shares data wirelessly with similar units): no
Power meter compatible (displays power data from compatible 3rd party ANT™ + Sport power meters): no

What's in the Box:

Forerunner SG305
Heart rate monitor
Garmin Training Center® software
Docking cradle
Expander strap
AC charger
USB cable
Owner's manual
Quick start guide