Only for X230. If ordering X200/T400/X200T/W500, please order the 8GiB kit instead: https://minifree.org/product/8gib-ram-upgrade/
This is exclusively for the Libre X230 product. With more RAM, you can run more programs simultaneously and your system will generally be more responsive.
A 4GiB and a 8GiB module will be installed into your X230. You can also purchase this separately, if you wish, and install it yourself, or purchase it with a laptop and Minifree will pre-install this upgrade for you. Price is in US dollars
Other laptops (e.g. Libreboot X200/T400) only take 8GiB max. For those, you might consider this instead: https://minifree.org/product/8gib-ram-upgrade/