Asus has launched the UnLimited or UL range of thin-and-light laptops that the company says have been designed for long battery life.

The UL laptops update an earlier line of U-series devices designed around CULV (consumer ultra-low voltage) microprocessors from Intel. Both series were designed with Apple's MacBook Air in mind, thin and light for portability.

Some laptops in the Asus UL family have features the MacBook Air lacks, such as lower prices, larger screens and DVD drives, but the MacBook Air beats the entire UL series on processing power.

Every laptop in the new UL series is less than 1in thick. They each have a brushed aluminum chassis and components designed to squeeze the maximum battery life out of the system.

"We hope to make this the new standard in laptop computers, thin and light with long battery life," said Jerry Shen, CEO of Asus.

Asus also may have made some breakthroughs in battery performance. The company claims the laptops offer up to 12 hours of power, depending on the configuration and usage.

Third party assessments of the devices were not immediately available. Some of the UL series laptops can hold 8-cell batteries, which will give far longer battery life, but also add considerable weight to a laptop.

All of Asus's UL series laptops come with the latest 1.3GHz Intel Core 2 Duo SU7300 processors and Intel GS45 chipsets inside as well as a 0.3Mp web cam and Microsoft Windows Vista Premium. They are upgradeable to Windows 7.

The UL50Vg laptop boasts the largest screen at 15.6in, and price, at $1,105 (£666). The laptop also includes Nvidia GeForce G 210M graphics, a 500GB hard disk drive (HDD) and a DVD Super Multi drive, and can hold up to 4GB of 800MHz DDR2 (double data rate, second generation) DRAM. The price is a suggested retail price from Asus and does not say how much DRAM is included in that price.

Asus said the prices were for the Taiwanese market and declined to name prices for other markets because tariffs and other factors mean prices vary.

The UL80VT is a 14in laptop with nVidia GeForce G 210M graphics, a 500GB hard disk drive, DVD Super Multi drive and up to 4GB of 1066MHz DDR3 (double data rate, third generation) DRAM, while the 13.3in UL30A has a 500GB HDD and up to 4GB of 1066MHz DDR3.

The UL20A is the entry-level machine and has a 12.1-inch screen, 320GB HDD, up to 4GB of 800MHz DDR2, and a suggested retail price of $980 (590).

The laptops are expected to be made available later this month.

Laptop buying advice

See all laptop reviews

See also: Asus Eee Keyboard to hit shelves in October