Liquid Impression Porous Point Pen combines function and style in an attractive design. Includes a tough, plastic tip that holds up to extended use. Uses environmentally friendly, water-based pigmented ink. Barrel features a visible ink supply that allows user to monitor ink levels. Ink is non-refillable and non-permanent. Available in ultra-fine and medium points. Conforms to ASTM D4236. Set includes 2 black, 1 blue and 1 red marker.