The cap of each pen contains a power 'Black- Light'UV beam, which illuminates the message. Each pen contains invisible ink, UV lamp, 4 x batteries for 36hr battery life! This Secret Message Writing Set is super cool! Pack 190 x 120mm

• The cap of each pen contains a power 'Black- Light'UV beam, which illuminates the message.
• Each pen contains invisible ink, UV lamp, 4 x batteries for 36hr battery life!
• This Secret Message Writing Set is super cool!

The cap of each pen contains a power 'Black- Light'UV beam, which illuminates the message.NPW