• The Apple Watch Ultra can use any bands made for 49mm, 45mm, and 44mm watches.
• If you are looking at a band in the online Apple store and it doesn’t show a 49mm size compatibility but it does show 44mm or 45mm, it should work with the Ultra.
• If you already have 44mm/45mm bands you want to use with the Ultra, keep in mind that it’s a bigger watch that will affect how the band fits around your wrist. For example, bands that stretch to fit and do not use a buckle, button, latch, or some other method to connect ends (like Apple’solo loop) might not conform to your wrist as they do with the regular Apple Watch. But they technically are compatible.