DynoCrafts Liquid Chalk Markers, 6mm Reversible Tip, 10-pack, Assorted Bright Colors, Non-Toxic 10 vivid liquid chalk markers  6mm tip is reversible: bullet and chisel Non-toxic, low odor, and long lasting (8 grams) - ink is quick to dry and dustless. Cap design prevents tip damage. It is important to always test a small area to ensure marker will wipe off before continuing use Erasable on non-porous surfaces such as glass, whiteboards, mirrors, acrylic, metal, vinyl chalkboard stickers, and chalkboard contact paper Permanent on porous surfaces - many chalkboards are porous and not suitable for liquid chalk - Please test a small area before using to ensure marker will erase. Other porous surfaces include, but are not limited to: wood, paper, fabric, and concrete.