Stretchable yarn interwoven with silicone threads designed for ultracomfort with no buckles or clasps. footnote ¹ The Barton adapter appears to be and feels the same as what you’d discover on any Apple Watch band with metal components. It fits perfectly into the Watch, lining up flush with the edges. https://allhealthmarket.com/product/aeahmarket/appleband/silicone-strap-for-apple-watch/apple-watch-slim-band-compatible-with-41mm-40mm-38mm-42mm-44mm-45mm-iwatch-strap-for-se-series-7-6-5-4-3-2-1-for-women-men/