Some smartwatches/fitness trackers have had the battery in the band - such as the Microsoft Band. It seemed to result in a fairly thick and inflexible strap, w

Some smartwatches/fitness trackers have had the battery in the band - such as the Microsoft Band. It seemed to result in a fairly thick and inflexible strap, with limited length adjustment. It was generally panned by reviewers for its bulk, although a microsoft-loving large-wristed friend of mine reported it was just fine.