The Staedtler Lumocolor permanent duo 348 B is a permanent marker with two tips for writing and marking on almost any surface. It combines a fine F tip of about 0.6 mm with a chisel M tip of about 1.5 to 4 mm, so you can switch between detail work and broader lines in one pen. The black ink dries quickly, is waterproof and smudge-resistant, and the marker is refillable. It suits office labelling, workshop marking, and everyday multi-surface use when you want one versatile Staedtler marker.