inside milling attachment

Hi
While surfing the net I found this site. They have attached a small
auxillary milling head to the side of a cnc taig mill which will
engrave in the inside of a tube or ring. it supposedly runs at up to
15,000 rpm's. I called but they were not very friendly. Can anybody tell me
what this device is or how its made?


http://www.5xj.com/cnc/Mill_id2.jpg

Thanks
Steve Ross