The ImmPrint™ Histology Pen is a solvent-resistant permanent marking pen designed for writing on frosted glass microscope slides, tissue cassettes, and most hard surfaces. The high-density, fast-drying, black ink resists most organic solvents encountered in histological applications, such as alcohols and clearing agents. Unlike other pens commonly used for histology, the ImmPrint Pen has a smooth writing tip that resists drying out.