(Image credit: Future)

It's hard to know what constitutes a good deal during Amazon Prime Day sales, although great deals on the best running watches and sports watches do tend to show up every year.And right now, you can save $100 on the Coros Pace 3 for just $199 at Amazon. It's a generation older than the recently released Coros Pace 4, but you get a great value sports watch for runners and triathletes, accurate, insightful tracking and top battery life.This deal could go at any time during the Prime Day sales, but you can grab it below right now.There's a time and a place for an upgrade, but sometimes the differences aren't worth the money for some people, and you might be deciding whether or not that's the case for you.The Pace 3, 4 and Pro models all offer similar sports tracking and training analysis features, but there are some key differences in design and navigation.The three watches have lightweight, slim designs made from plastic with glass screens. The Coros Pace Pro is the largest watch with its 1.3in display compared to 1.2in on the Pace 3 and the Coros Pace 4. The Pace 4 and Pace Pro both have AMOLED displays, which are brighter than the MIP display on the Pace 3, but the 3 is still easy to read when outdoors, especially in sunlight.The Pace 3 doesn't have a mic as the 4 does, but it does have a barometer, multi-band GPS tracking, and a 5ATM waterproof rating, like the others. The Pace 3 is charged directly with a cable, whereas the Pace Pro and Pace 4 both come with an adapter you can attach to a USB-C cable.Pace Pro and Pace 3 lasted roughly five or six days on a charge during testing, which was longer than the 4.