Measure the duration of both of those straps together in millimeters (mm). You may also evaluate each separately and include them up to have the overall strap size. Do not incorporate the buckle in the strap duration measurement. Screening conducted by Apple in August 2023 applying preproduction Apple Watch Ultra https://allhealthmarket.com/product/aeahmarket/appleband/silicone-strap-for-apple-watch/apple-watch-silicone-strap-band-44mm-40mm-45mm-41mm-42mm-38mm-45-mm-accessories-correa-bracelet-iwatch-series-6-5-4-3-se-7/