Ink Color Violet, Green, Red, Blue, Black, Pink, Yellow Target Audience Child Special Feature Washable Color 14 Stck Number of pieces 14 Letter Print design About this item Invisible writing: send invisible messages, then render - visible ones using UV light. Thus, hidden messages can be sent without being detected. Ideal for guest gift: Kids love detective and spy games with these invisible ink crayons. Invisible ink pens provide you with a variety of fun activities like treasure hunting. Safe and tasteless ink, healthy toy for your kids. You can write anywhere: on t-shirts, paper, skin. Permanent but washable (please do not use on any special surface like glass or smooth plastic film etc). 14 crayons in 7 different colors: Battery included and installed. The different colors make the activity more exciting and fun. The ink inside the pen is the same color. Parents can buy it for their child's party at home. In schools, teachers can buy it for school activities. It can also be used to garnish a lucky bag or a Christmas stocking.