Acrilex Double-Tip Permanent Markers are perfect for permanently marking surfaces such as CDs, DVDs, plastic, glass, metal, and wood. With dual tips, they offer versatility for different types of strokes. The fine tip, with a 0.4mm line and a 0.7mm nib, is ideal for detailed and precise markings. The broad tip, with a 1mm line and a 2mm nib, is great for covering larger areas or creating more visible lines. These markers are perfect for projects that require durability and precision on various materials.