secret pen

Most secret and spy pens use common visible ink colors such as black, blue, and red. Some multi-color models let you switch among red, black and blue in a single pen, while other designs pair one visible color (often blue) with an invisible-ink option for secret messages.

Typical office security-pen kits include the pen (often with a rubberized grip), a base or adhesive anchor for mounting, a security chain (commonly around 26.5 inches) to keep the pen attached, and many packs also include extra refills.

Reveal tools vary by set and commonly include decoder lights or built-in ultraviolet (UV) lights and decoder markers. These accessories let you read invisible-ink messages by illuminating or marking the hidden writing.

It varies by model: some multi-function pens offer three selectable visible colors (typically red, black, and blue), others provide two blended gel colors, and some dual-function pens pair one visible color with an invisible-ink option.

Common features include invisible ink paired with a decoder (UV/decoder light or decoder marker), color-changing or disappearing ink, and—in some kits—extras like a magnifying glass, a hidden compartment, or a removable “Top Secret” stamp.

Common tip sizes include Medium and the metric measurements shown, such as approximately 2.05 mm and 3.3 mm. Available sizes depend on the specific model.

Typical novelty effects include color-changing ink, disappearing/vanishing writing, two-color swirl or blended gel effects, and invisible-ink messages that are revealed with a decoder light or decoder marker.