ThinkPad X series

The X series of laptops and convertible tablets are part of Lenovo's ThinkPad product line. The ThinkPad X series is traditionally the range best designed for mobile use, with ultraportable sizes and less power compared to the flagship ThinkPad T series. Formerly an IBM brand, Lenovo acquired the ThinkPad brand following its purchase of IBM's Personal Computing Division (PCD) in 2005. IBM announced the ThinkPad X series (initially the X20) in September 2000 with the intention of providing "workers on the move with a better experience in extra-thin and extra-light mobile computing." The ThinkPad X series replaced both the 240 and 570 series during IBM's transition from numbered to letter series during the early 2000s. The first X Series laptops were "slimmer than a deck of cards" and "lighter than a half-gallon of milk", despite the presence of a 12.1-inch Thin-film transistor (TFT LCD) display. These design values—thin and light—continued to be integral to the ThinkPad X-series laptops' design and marketing, even after the purchase of IBM's Personal Computing Division by Lenovo. The last X-series ThinkPad released by IBM was the X41 tablet in 2004. Also, the first X-series ThinkPad released by Lenovo were the X60, X60s laptops and X60 tablet in 2005. The ThinkPad X-series laptops from Lenovo were described by Trusted Reviews as "combining an ultraportable's weight and form factor with a durable design." The X-series laptop styles include traditional ultraportables, as well as convertible tablet designs. According to Lenovo, the ThinkPad X-series laptops include low power processors, offer long battery life, and several durability features such as a Roll Cage (Magnesium Frame around the Display), magnesium alloy covers, and a spill-resistant keyboard but currently lacks a replaceable battery and upgradable RAM slots. Battery configuration