The Ultrahuman Ring Pro advertises up to 15 days of battery life. For comparison, the Ultrahuman Ring Air lasts 4-6 days on a charge according to official numbers. That's a massive upgrade but isn't the end of it either. The new ring comes with a new Pro Charger, which extends the ring's endurance up to 45 days.
The Ring Pro is Ultrahuman's third-generation smart ring, and promises up to 15 days of battery life before needing to recharge, alongside 250 days of on-device health history storage. Those are some significant improvements compared to its predecessor, the 2023 Ring Air, which provides 4-6 days of battery life and several days of offline data storage.
In short, you can use voice commands to log events throughout your day - what you ate, what you drank, the supplements that you took, any workouts that you did, even subjective feelings. Previously, you had to pull out your phone to do that. That extra bit of friction could cause you to put it off for later and forget to log important things.