Allergy Alert Safety Tattoos. Each tattoo allows you to use the included pen to write your contact number and other details onto the tattoo. Kids love the colourful and fun designs, parents love the ease of use and protection these tattoos provide. Each tattoo is a micro-thin elsatomer that is applied like a sticker to the skin, simply wipe skin, peel backing off tattoo and apply. It is instantly waterproof and can stay in place for up to two weeks, even on the most active of children.