This was the first ‘triathlon’/duathlon watch from Garmin. It’s still a current model and has stood the test of time. There are newer Garmin models. However the 310XT is usually available at a VERY good price and is superior to several other current products – that’s why I am mentioning it now.
Positives: It supports all the basic ANT+ sensors – power, HR and cadence. GPS and general accuracy are good. You can set a long run-bike-run-bike etc BRICK session…longer than later models.
Negatives: It has no real swim functionality to talk about although you can record swim time with it, even in a triathlon. It’s a tad big and orange. There are good ones and bad ones, I wouldn’t advise buying without some form of warranty. Earlier ones have firmware bugs and you must use the latest firmware.
Comments: Great value for money. This is pretty good as a duathlon watch. You will get nearly all the duathlon features you realistically need and it’s great as a standalone running or cycling watch.
Alternatives: This link covers some alternatives.
Detailed Review: This link covers my more detailed review of the Garmin 310XT.