These Liquid Chalk Markers are great for non-permanent designs and decorations on non-porous surfaces e.g. Windows Dark Boards Glass & Mirrors.Chisel stroke with 4-15mm widths.Fluorescent colours visible under UV light.Opaque and odourless water-based liquid chalk.Wipe off Virtually all Non-porous surfaces using a damp cloth.Contains 1x White 1x Neon Yellow 1x Neon Orange 1x Neon Pink and 1x Neon Green.To use keep the lid on the Marker and shake well. On piece of scrap paper pump the nib VERY gently until the ink starts to flow.