The Asus UX21 looks very much like a MacBook Air. The Asus UX21 is 17 mm at its thickest point, which just happens to be how thin the MacBook Air is. The difference is in power: the Asus UX21 packs a second generation Core i7 CPU while the MacBook Air is limited to just a Core 2 Duo. Even with an i7 the UX21 is claimed to last up to 7 hours. The trackpad is glass and buttonless, just like the MacBook Air.
It looks like the display is around 11.6 inches since the dimension and shape look almost identical to the 11.6-inch MacBook Air. Well, I think I’ll be eating my words when I wrote about this new Intel classification of notebooks called ultrabook: I dismissed it assuming it was just a more expensive netbook. The fact that ASUS was able to pack an i7 into a chassis the size of a MacBook Air is quite impressive.