Features Universal pen for use on almost all surfaces; Suitable for overhead projection; Can be wiped off film using a damp cloth; Water-soluble ink; Fast-drying; PP barrel and cap guarantee long service life; Airplane-safe - automatic pressure equalization prevents pen from leaking on board aircraft; Stand-up STAEDTLER box; Superb colour brilliancy; Lightfast colour black; Line width medium approx. 1.0 mm.; Refillable.