uni-ball Chalk Markers are a water-based marker with vibrant colours that are perfect for eye-catching designs. Ideal for non-porous Chalk Boards, apply to glass in pubs or restaurants both inside and outdoors, they are rain resistant and produce dense vibrant colour designs with great effect. The ink can be easily removed from non-porous surfaces using a damp cloth with mild detergent. Line width 1.8mm to 2.5mm, medium bullet tip. Pack of 4 pens with the following ink colours: red, yellow, blue and white.