Uni Liquid Chalk Markers utilise water-based pigment ink so you can mark on windows, glass, mirrors, plastic and metal surfaces with ease. The ink won't wash off in the rain, yet is easy to remove with a damp cloth. For permanent application the markers can also be used on chalkboards for a bold statement. This marker features a super fine 1.3 mm bullet nib. It is a great option for leaving notes on glass, mirror, plastic and other non-porous materials. The ink is rain-proof but can be removed with a damp cloth. This marker contains white liquid chalk ink. The ink is removable on non-porous surfaces. It's recommended to store these markers horizontally when not in use.