From the shape of vacuum tube, we hardly know what the USB gadget is. But obviously it has a damned cool appearance.
In fact, the USB gadget in the shape of vacuum tube is for bringing DTS(Digital Theatre System) to your PC or laptop. The USB gadget is named as X-Tube, which is designed by Hanwha Japan. It comes with a pair of headphones and DTS Headphone Deck application. After installing the application in your PC or laptop, and plugging headphone jack into X-Tube, you could enjoy the DTS surround sound.
X-Tube is priced at about $44 USD. You can get more details or purchase it at UMAZone.
Update: Now you can get the X-Tube for about $85 USD at GeekStuff4All.