The Securit Waterproof Chalk Marker was created for all the fans of the Securit Original Chalk Markers. They are waterproof, non-toxic, highly opaque white liquid Chalk Marker with a 2-6 mm chiselled nib. Non-smudging (when dry) and 100% resistant to rain. Suitable for non-porous surfaces. The markers are easy to use, simply shake, push the nib down, write or draw, and allow the writing to dry.