Staedtler Lumocolor 318 Fine 0.6MM Line Permanent Pen, 8 Shades

Universal pen for use on overhead film and almost all surfaces
Dry safe – can be left uncapped for days without drying up (ISO test 554)
Excellent smudge-proof and waterproof qualities on almost all surfaces
Supplied in handy stand-up desktop box
Fine line width approximately 0.6mm