Turn your ring stack into a smart one with the Oura Ring, now 15% off for Amazon Prime members. It tracks sleep, stress, activity, and more, and even includes your first month of membership free. Choose from several finishes. The 30-ounce Stanley Quencher is on sale at Amazon for Prime Day. You can get the color "Tigerlily Plum" for just $21.

The latest version of the Oura ring, the Oura Ring 4, is on sale today for Amazon’s Prime Day for as little as $297. This model launched last fall and has never been on sale since then. Today, all colors are 15% off if you buy them from Amazon.

If you're in the market for a reliable sleep tracking ring, but don't have the budget to splash out on the likes of Oura, the Amazon Prime Day sale is a great place to shop for more affordable alternatives, such as this FKGZJF Smart Ring available for just $69.98 at Amazon now.