Improving design is a key element in this series, as each Timeline laptop uses brushed metals instead of traditional plastics. In the past, Acer Aspire mainstream laptops were thick and clunky, measuring 1.5-inches in thickness. The new Timeline laptops are noticeably thinner, each of them measuring around an inch thick. As a result, they are also lighter than their predecessors. There were three Aspire Timeline laptops on display at the event, which will begin shipping at the end of April 2009: a 13.1-inch, a 14.1-inch, and a 15.6-inch form factor.