Uchida Bistro Chalk Markers are great to use on chalk board, dry erase boards, light boards, windows and windshields. The opaque, waterbased, pigmented formula is erasable with a damp cloth. Store in a horizontal position when not in use and make sure cap snaps on securely. Broad Carded Fluorescent Blue- Fluorescent color glows under an ultra violet light. 6mm bullet tip.