Mudra band is compatible with all Apple Watch case sizes. You can adjust the Mudra band length to fit wrist sizes ranging from 6 1/2 in to 8 1/4 in (165mm to 210mm).
Mudra Band is water-resistant but not waterproof. You can use it while doing dishes or washing your hands without any special care, but it shouldn't be taken into a pool for swimming.
Mudra comes with it's own battery and does not drain your watch battery. Since the band communicates directly with your iPhone the battery power will be affected as when using other Bluetooth devices.
Mudra Band's battery lasts for at least 2 days of regular use. It will take about an hour to charge.