The Winsor & Newton Cotman Brush Series 666 is a high-quality brush designed for professional artists. This 3/8 inch brush is made from a blend of synthetic fibers that provide excellent color carrying capacity and a smooth, even finish. The brush is designed to hold its shape and spring back into shape after use, making it ideal for a variety of painting techniques. The brush is also easy to clean and maintain, making it a great choice for both beginners and experienced painters. The brush is suitable for use with watercolor, acrylic, and oil paints, and can be used on a variety of surfaces, including canvas, paper, and wood. The brush is also lightweight and comfortable to hold, making it easy to use for extended periods of time. The Winsor & Newton Cotman Brush Series 666 is an excellent choice for any artist looking for a reliable and versatile brush.