These specially made markers are perfect for making permanent, Ultra-Fine line details in micro-spaces or on unusual/challenging surfaces. Excellent for labelling vials, U-2D MicroSample Management Systems and other laboratory devices. These "pens" can be used to make precise, long-lasting marks wherever there is a need for waterproof ink that will write on non-porous surfaces. Laboratory Markers features: A fine line nib with a protected tip that will not split. Chemically stable and waterproof alcohol-based ink. Low odor and fulfills non-toxicity requirements. Permanent on most surfaces. Alcohol based cleaners can remove ink from non-porous surfaces. Writes on glassware, vials, plasticware, wood, cellophane, glossy sheets, films, paper, metals and other hard surfaces,