You brush off your coat and walk back onstage.
"What a show this evening. What a show. I want to warn you, this next item will require demonstration. May I kindly ask you to turn off your phones and other wireless devices? Thank you."
You reach into you coat pocket and pull out a small device.
"Next on the block is this little toy."
You push the button. Every surveillance camera in the room overloads, glass cracking and shooting off an array of sparks.
"What it does is send a signal to wireless devices. For espionage, it can serve to destroy cameras, probes, automated weapon systems."
A dummy is rolled out with a Bluetooth headset on its ear.
"Or if necessary."
You push the button again. The headset detonates, blowing a hole in the dummies head and embedding plastic shrapnel on its skin.
"A bomb. These are still prototypes. Due to the experimental nature of these devices, we only have ten for sale at one hundred thousand a piece. Do we have any takers?"