24 Each of 12 Original Colours, 0.6mm line width. Suitable for detailed line drawings and illustrations. Washable ink. 21 day cap off time. Ventilated cap. Washable pens are water-based and ink may wash out of clothes. Water soluble pens mean that the ink is water-resistant after drying and will not wash out easily. Colouring, Felt and Marker Pens Do not store near a heat source or in a hot cupboard as it may dry out the ink inside the barrel.