A light, soft extension material that does not reflect light and gives the braid a matte finish is:

Yarn is known for its light and soft texture, making it a suitable choice for weaving and braid extensions. One of its notable characteristics is its matte finish; it does not reflect light as some synthetic materials do. This quality not only enhances the natural appearance of the braids but also allows for versatility in styling, as it can blend seamlessly with various types of hair. The matte finish of yarn helps in achieving a more understated and sophisticated look, which is often desired in braided hairstyles. Additionally, yarn is available in a variety of colors and weights, allowing for creative expression and customization in braiding techniques.