Invisible Ink Pen Party Favors: the package includes 5 pcs UV blacklight flashlights ( batteries not included) , each measuring approximately 3.4 x 1 inch, and 5 pcs UV ink marker pens, each around 5.7 x 0.4 inch; Customers can write their secret messages on the paper, which can only be revealed by shining it with UV light, providing lots of fun for parties and family games Reliable and Safe: this UV flashlight is made of quality waterproof and impact aluminum alloy, ensuring that you can use it safely even on rainy days; This spy pen uses washable and safe ink and is equipped with a sturdy plastic body, so you can use it with confidence while having fun UV Markers for Blacklight: the invisible ink pen set is suitable for detective games and keeping secrets, and this set of blacklight UV markers is a addition to any family gathering, can be applied for exciting activities, to spark imagination, or as fillers for party favor bags Multipurpose Use: the disappearing ink pen and light flashlight are not only suitable for birthdays, parties, Christmas, New Year, Easter and various occasions, but also suitable for detecting animal urine, pet stains, food stains, room cleaning, easily verify currency, gas leaks, and so on Usage Instructions: while our invisible ink pen with light add fun and functionality to your life, it's important to note that they are invisible or colorless in normal light, and to witness the glowing effect you must have a black light; Please note: this product does not include batteries, you need to prepare 3 AAA batteries yourself Features: UV flashlight and pen set: Our black light UV flashlights and invisible ink pens can create an invisible message, and while the ink is invisible in normal light, it displays invisible message or things under a black light. This sparks their imagination, making it a nice addition to any party favor Invisible ink pen favors: The black light flashlight mini set is not only suitable for birthdays, parties, Christmas, Halloween and various occasions, but also suitable for detecting animal urine, pet stains, food stains, room cleaning, easily verify currency, gas leak, and more. Specifications: Main materials: Black light UV flashlights: aluminum alloy Invisible ink pens: plastic Color: black Size: Black light UV flashlights: about 3.4 x 1 inch Invisible ink pens: about 5.7 x 0.4 inch Package includes: 5 x Black light UV flashlights 5 x Invisible ink pens Notes: Manual measurement, please allow slight errors on size. The color may exist a slight difference due to different screen displays