Spy pens are compact and pocket-friendly. Lengths shown in listings are around 5 to 6 inches (examples include approximately 5 in, 5.5 in, and 6 in), making them easy to carry in a pocket, pencil case, or bag.
Reveal tools commonly included are decoder lights or built-in UV (ultra-violet) lights. Product descriptions frequently mention either an included decoder light or an integrated UV light to make invisible ink visible.
Package quantities shown across listings include packs of 4, 6, and 12 pens.
Some spy pens are multi-ink, such as 3-in-1 retractable pens that switch between red, black, and blue. Others pair a regular colored or blue ink side with a separate invisible-ink side for secret messages.
Playful features include character-themed colorful designs and secret-message play using decoder lights. Listings explicitly note these pens are great for prize boxes, party favors, and back-to-school kits.
