For use on conventional slate chalk board and glass these Pentel Markers contain liquid chalk which removes easily with a wet cloth. Suitable for both indoor and outdoor use the markers feature a valve action for a smooth controlled ink flow. Ideal for displays decorations menus information and more the chisel tip writes a variable line width of 1.5-4.0mm. This assorted pack of 4 chalk markers contains red yellow blue and white. Ideal for use on blackboards whiteboards glass ceramic metal and non-porous surfaces For indoor and outdoor use Valve-activated flow no blobbing or leaking Chisel tip for a 1.5 - 4.0mm line width Barrel colour: Black Ink colour: Assorted Pack of 4 Made with a minimum of 69% recycled materials Pigment-based Ink Remove with damp cloth or non-bleached-based household cleaner and a non-scratch scrourer