These heavy-duty, soft tip disposable pens write on glass, ceramics, metal, plastics, and paper. The oil-based marking paint resists washing, weathering, mild acids, and alkalies. Pens withstand autoclaving at 121°C (250°F). Pens operate within the temperature range of 4 to 49°C (-5 to 125°F). Mark is approximately 1mm (0.040") wide. Snap-on caps indicate ink color.