Available Sizes in Each Apple Watch Series:
Series 1: 38mm or 42 mm
Series 2: 38mm or 42mm
Series 3: 38mm or 42mm
Series 4: 40mm or 44mm
Series 5: 40mm or 44mm
Series 6: 40mm or 44mm
Series SE: 40mm or 44mm
Series 7: 41mm or 45mm
The same bands are compatible with case sizes 38mm, 40mm, and 41mm due to them all having the same depth. The same goes for case sizes 42mm, 44mm, and 45mm.
When buying a protective case for your Apple Watch, make sure you buy the exact mm as shown on the back of your watch.
* Make sure to check the back of your Apple Watch before purchase to ensure you get the right size!