from the seller's web site...
"Our covert Wireless Spy Cam Pen is ideal for undercover assignments, wear it innocently on your shirt pocket, place it on a desk, attach it to an organizer, or just start writing with it like you would a normal pen — all while transmitting live high-quality color video images. It’s the size of a regular pen, so you can bring it with you anywhere.
The Pen Camera cleverly conceals a quality color video camera inside a working pen. Minimal illumination makes it difficult to detect that you’re using it for anything more than writing.
To start transmitting, simply click the top of the pen, yeah it’s pretty cool. Just attach the receiver to any TV or VCR for easy recording, or even a security monitor.
This little hidden camera in a pen has a transmission range of more than 300 ft." (more)
Why do I mention it?
So you will know what you are up against.