Ideal for use on all blackboards, whiteboards, glass, ceramic, metal and non-porous surfaces Imitates real chalk Fade-resistant Wetwipe formula means ink will not erase accidentally Waterproof after drying, so it can be used inside or outside Remove with a wet cloth (or non-bleach based household cleaner) Extra tough chisel style valve tip means crisp clean edges to lettering with a variety of looks, regulated ink flow to eliminate blobbing and leaking, and will retain its shape without fraying even when used on uneven surfaces Wallet of 7 contains blue, red, green, yellow, orange, violet and white