This subscription-free smart ring rivals Oura and is under $300 right now

The RingConn Gen 2 offers a robust set of health-tracking features and a full week of battery life. During Amazon's Big Spring Sale, it's $45 off right now.

• The RingConn Gen 2 is a subscription-free smart ring that retails for $300.
• It monitors your sleep, activity, stress, and vitals, and it's got a marathon battery life.
• The only downside is the user interface feels underdeveloped.

Amazon is discounting the RingConn Gen 2 by $45, taking down the price of the smart ring from $300 to $255 on the first day of the Amazon Big Spring Sale event that runs through March 31.

Also: The best Amazon Spring Sale deals live now 

Most smart rings these days claim to offer marathon battery lives but often fall short of their promise. Many smart rings claim to last a week's worth of battery but only make it to five ...