An anonymous reader writes "Sony claims that both the new 11.6-inch and 13.3-inch models of its Haswell-equipped Vaio Pro ultrabooks are the world's lightest. The 11.6-inch model weighs in at 1.9lb (0.87k , where as the 13.3-incher is a little heavier at just 2.33lb (1.06kg). But it's the battery life on offer here that really makes the new Pros stand out. The 11.6-inch Vaio Pro offers 11 hours of battery life as standard, while the 13.3-inch achieves 8 hours. However, Sony is also offering a sheet battery you can connect to the base of the ultrabooks. On the 13.3-inch Pro that increases battery life to 18 hours, but on the 11.6-inch you get a true day-long amount of juice with 25 hours of battery life claimed."