The 8pcs Deep Hole Markers Set features 20mm long nibs made of ABS plastic and Tungsten Carbide, perfect for marking on metal and wood surfaces. These waterproof woodworking pens are ideal for precise and durable marking, suitable for various crafting and art projects. Each pen is 13.7 cm in length and 1.5 cm in width, ensuring comfort and control while using. The set includes 8 multicolor pens, making it versatile for different marking needs.