This pack of 4 liquid chalk markers from uni-ball are ideal for non-porous Chalk Boards and glass in pubs or restaurants both inside and outdoors. They are rain resistant and produce dense designs with great effect. The ink can be easily removed from non-porous surfaces using a damp cloth or mild detergent.. Line width 1.8mm to 2.5mm. Medium bullet tip. Liquid chalk - writes on, wipes off. Use with; blackboard, whiteboard, glass mirror, plastic, metal. Bullet TipPack Dimensions (mm) H 150 W 70 D 20