HP Slate Pro 8 and 12 inch Tablets

HP has just introduced its new Slate Pro tablets that come with their own styluses. They come in two sizes 7.9 and 12.3 inches. The stylus uses an ultrasonic sound technology. The interesting part of this new stylus is that it can write on a real piece of paper and your notes will show up on your tablet screen. I assume that the stylus needs batteries, but I'm not sure what kind.  Here's an article on the new tablets.
www.androidcentral.com/hands-hps-pro-slate-8-and-giant-12-inch-one-and-its-crazy-stylus