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.

[5] 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.

[7] 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[7] but currently lacks a replaceable battery and upgradable RAM slots.

All new internal design, slim-version dropped, SVGA screen option dropped, Tualatin CPUs, faster (Mobility Radeon 7000 8 MiB) GPU, Communications Daughter Card/CDC slot, optional FireWire and/or WiFi on some models, 133 MHz FSB, maximum RAM increased to 640 MiB.

Same as the X22 but with faster processors (800 or 866 MHz), bigger hard drives up to 30 GB, Bluetooth, and the IBM Security Sub System on selected models.

X30 updated to the Intel Centrino platform, Pentium M CPUs, faster RAM (DDR PC2100), better GPU (ATI Radeon 7000) and more VRAM (16 MiB), USB 2.0, 2nd USB port on the left side, Gigabit LAN introduced on some models, IBM Security Sub System on some models.

It was also more powerful than the X40 and X41 units, due to the use of faster full-voltage Dothan processors and standard 2.5-inch 5400/7200 RPM hard drives.

This gave the X60s a lower active temperature and longer battery life in exchange for reduced performance.

[22] It differed from the standard X200 in being lighter, having longer battery life, and running more quietly due to an "owl fan" design for cooling taken from the X300.

[23] The X200s was available with more than half a dozen different CPUs and three screen options; the top of the range was a WXGA+ LED-Backlit TN Panel.

It is distinguished from other ultraportable laptops by its use of LED backlighting, removable battery, solid-state drive, and integrated DVD burner.

The second was light-emitting diode (LED) backlighting for flat-panel displays which would improve battery life and image quality.

The ThinkPad X100e was released in 2010, with Engadget calling the laptop "the perfect solution between a netbook and a larger 13- or 14-inch ULV ultraportable".

[31] The X100e, however, despite the choice of colors, retained the "angular edges and boxy build" which "scream traditional ThinkPad design".

[31] The specifications[32] of the X100e laptop are given below: A modified and re-branded low-cost version of the Lenovo X100e, named the Mini 10 was issued to all Year 9 students in Australia at the start of 2010.

[35] Notebook Review had similar views about the X201 tablet in terms of both performance and battery life while indicating the display was superior to that of the X201 or X201s.

[4] It was praised for its battery life, performance, low weight, display, keyboard,[41] and significantly improved temperature control.

"[43] The laptop's specifications[13][44] are given below: The X220i uses the same motherboard and chipset as the standard X220 but has a less powerful Intel Core i3 processor, compared to the i5 and i7 options available for the X220.

The base configuration uses an Intel Sandy Bridge 2.5 GHz Core i5-2520M (up to 3.20 GHz) with 4 GiB of RAM (up to 8 GiB), SATA SSD or hard drive, Intel Integrated HD Graphics, USB 3.0, backlit keyboard, 802.11 b/g/n WiFi and an average of eight hours of battery life.

[56][57][58][59] A special edition laptop was provided for Australian Year 9 students as part of the Digital Education Revolution (DER) program in 2012.

The new keyboard design became a controversial topic in the ThinkPad community along with the locked-down BIOS that discouraged third-party components including batteries or WLAN cards.

More akin to later X240 instead of the X230, it gained many of the design cues later found on the X240 and were equipped with Intel 3rd Gen ULV CPUs, a thinner and lighter design while on an Ultrabook, and Power Bridge, which adds a secondary internal battery and allows hot swapping the main external battery without shutting the system down.

With a slightly boosted battery and maybe a lower starting price, this could be a serious contender for my all-around favorite thin laptop.

[69] In November 2012, Lenovo announced a touch-screen variant called the ThinkPad X1 Carbon Touch designed for use with Windows 8.

We also found that the solid-state drive delivers equally strong read and write speeds (551 MB/s and 518 MB/s, respectively), which we noticed the last time we tested an Ultrabook with an Intel SSD.

The ThinkPad Helix was released as an option for corporate IT buyers who were looking for the power of a high-end Ultrabook and the mobility of a tablet.

The ThinkPad Helix featured a tablet powered by Ivy Bridge components, a docking keyboard, and a Wacom digitizer stylus.

However, some reviewers criticised the limited port selection without Ethernet or USB-C, soldered RAM up to 8GB, and high starting price, at around £1,200.

1920×1080 IPS Touch (on-cell) Lenovo ThinkPad X280[97] is the first in the X line to feature charging and docking to USB-C Thunderbolt.

Unlike previous models in the series, this has soldered RAM, a non-removable battery, and no built-in RJ45 Ethernet port (although one is available via an extension cable).