Durable Material: These eraser pens are made of sponge, felt, and ABS. The black pen tip is sponge-based, while the white tip is felt-based, which is soft and smooth and will not damage the drawing paper. The sturdy plastic shaft makes them durable, comfortable to hold, and reusable. Double-Head Design: The friction sponge brush adopts a practical double-head design, which aims to handle details and depict the block surface when sketching. A large-sized soft black sponge head is suitable for stains, and a small-sized black sponge head is suitable for handling local details. A large white tip is suitable for the transition of dark or light surfaces, while the small white tip is suitable for rubbing details. Practical Size: The sketch friction sponge brush has two different sizes to meet your needs. The large pen tip measures about 1.2cm in diameter and the total length is 14.5cm; the small pen tip measures about 0.6cm in diameter and the total length is 13.8cm. Package Contents: 6 pieces washable double-headed sponge brushes, with double-headed design, with 2 different sizes to meet most of your artistic needs. For artists or painting enthusiasts, these sizes are practical and versatile, providing more creative space. Wide Application: This blender sponge pen set is a good tool for artists, students, and beginners. It simplifies blending and shading, allowing you to create beautiful gradients and shading in your artwork. Suitable for a variety of occasions, from art projects and school assignments to amateur crafts.