1st in the world 100% merino wool Apple watch band ensures 24/7 comfort and style, prevents wrist from sweating, gets more durable with use and time, keeps watch closer to your pulse, will outlast other material bands. You will never want to go back after using this one. Merino wool also has anti bacterial properties. Band has textile safety OEKO-TEX standard 100 and is safe to use on skin. Suits all series (including series 8, Ultra) apple watches: smaller case (38, 40, 41 mm) or larger case (42, 44, 45 mm).