That's why I've searched through all the Amazon Prime Day deals to find you the best chest strap monitors I've tested that ...

The Amazfit Helio strap uses the same app as high-end smartwatches, but strips down the hardware to a simple sensor (for no subscription).

The Garmin Forerunner 255 has one of the biggest smartwatch discounts for Amazon Prime Day 2025, with the Whitestone edition ...