Even better, though, is that the new Pebbles have a battery life that can last a month on a single charge. Yes, Pebbles plural, because there's a lower-end black and white model and a fancier color one with heart rate monitoring.

Pebble is back and is betting that a 30-day battery life can shake up the smartwatch market dominated by Apple Watch.

The Core 2 Duo and Core Time 2 are two watches that run Pebble OS and have up to 30 days of battery life. They won't be available for long.