2 in 1 Invisible Ink Pen UV Black Light Combo (Purple)

Great!

Egg

This pen is such a great idea! It can be very finicky, though, with the UV light. The battery casing is quite particular about how the spring and batteries fit together, and if it's not exactly right, the light will work intermittently or not at all. It took me more than a few tries and lost batteries to get it right.

Of course my kids loved this and use it a lot for "secret spy missions." The only reason not five stars is because the cap starts off so impossibly tight at first. got a little looser with use.