Measure the duration of each straps with each other in millimeters (mm). It's also possible to measure each separately and add them up to have the whole strap duration. Don't include the buckle as part of your strap length measurement. Flaws but not dealbreakers: The Mustang has only eight holes https://allhealthmarket.com/product/aeahmarket/appleband/business-real-leather-loop/real-leather-strap-for-apple-watch-band-44mm-40mm-41mm-45mm-42mm-38mm-49mm-wrist-bracelet-iwatch-series-8-se-7-6-5-4-3/