Apple Watch Ultra is also suitable with 45mm bands, but 45mm bands should only be worn for relaxed, every day wear. Stretchable yarn that’s interwoven with silicone threads and designed for convenience, with no buckles or clasps. footnote ¹ Make sure to use a delicate and hypoallergenic liquid hand soap. https://allhealthmarket.com/product/aeahmarket/appleband/business-real-leather-loop/retro-leather-strap-band-for-apple-watch-series-ultra-8-7-6-5-4-se-42-44-45-49mm-bracelet/