Big & broad tip 15mm line. These highly opaque, light-fast and waterproof chalk markers are effective on surfaces such as glass, plastic, metal, wood and stone. These prominent liquid chalk markers produce a chalk look without a chalk mess, are a valve-action and work exceptionally well on blackboards (chalkboards) and whiteboards and can be removed using our Chalkboard Cleaner. Mainly used in pubs, bars and restaurants, with some classy artwork, these markers can make your business stand out from the rest!