The set contains 2 pens with invisible ink. The message is only revealed when you shine the light in the pen lid onto the ink.
Give one pen to a friend and keep one for yourself so that you can write secret notes to each other
Each pen uses 3 LR41 Lithium batteries which can be replaced by unscrewing the top section of the pen
WARNING! Choking hazard, small parts, keep away from children under 3
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