La Oura Ring 4 is a connected ring equipped with health and sleep sensors currently on sale on Amazon for 219 euros, down from 399 euros, during the Prime Flash Sales. The device tracks health data such as sleep quality, heart rate, stress levels, body temperature, and recovery. It comes in multiple sizes to fit different finger sizes, and users are advised to carefully check their finger size before ordering. Oura has improved comfort by flattening the inside of the ring, unlike the Ring 3, which had rounded sections that could leave marks. The Smart Sensing system, with 18 signal channels, adjusts measurements to the ring's micro-movements throughout the day. The ring has a battery life of 5 to 6 days with its proprietary charger. However, it does not include a screen or built-in GPS. The Oura app is described as user-friendly and provides detailed analysis of the collected data. Full access to features requires a monthly subscription of 6 euros. La Oura Ring 4 is recommended for users interested in health and recovery who want a discreet and comfortable wearable. Regular athletes may find the lack of GPS and the accuracy of heart rate during intense exercise frustrating. To take advantage of the Prime Flash Sales, it is necessary to be a member of Amazon Prime, with a 30-day free trial available.