Just a quick heads up to anyone considering any of the older LeTv x800 or x900 devices please do not purchase the US (international) version as it appears LeEco has dropped support for those devices, this has left owners stuck on a older lollipop ROM with many bugs, yes you can instal a custom recovery and some of the few ROMs available but almost all developers are dropping development for the US version because LeEco won't release the source so improved Marshmallow ROMs can be ported. I love the sound on this device and it's even better with a custom ROM from the x900 especially battery life but please if you decide to get one to play with get the Chinese versions which are getting updates and bug fixes, play store can be easily installed and sure you will not have LTE but HSPA+ is fast enough IMO.
http://www.letv.re/forum/145-rom-us/
At least there is some port rom from CN version for latest 18S with MM.