For Apple Watch Series 4 and 5, Apple increased the size of the display of both the larger and smaller watch sizes from 42mm and 38mm, respectively, to 44mm and 40mm. Additionally, for Apple Watch Series 7, Apple increased the size of the display of both the larger and smaller watch sizes from 44mm and 40mm, respectively, to 45mm and 41mm. Please refer to the Sizing Chart Guide to find the right size amBand Watch Band for your Apple Watch size and series.