HPLC screw-top vials with write-on patches are a common type of sample vial used in high-performance liquid chromatography (HPLC) for storing and injecting samples.
Provides a convenient area to label the vial (e.g., sample ID, date, concentration).
Resists solvents and smudging better than writing directly on glass.
Prevents confusion in sample identification, especially when working with many samples