The widest part is about 12cm. The elastic is 17cm long. The material is 100% cotton. While made with care, as this is handmade, there may be noticeable stitches or markings. These may become less noticeable with time or washing, but as this is not a mass-produced item, we do not recommend purchase for those who are very particular. We hope those who understand handmade items will consider purchasing.