I had a 120gb sandisk ssd in my ux31a zenbook, and it was quite slow and space wasnt nearly enough for me. So I went ahead and installed a Crucial MX300 275GB M.2 (2280) ssd using the full length adapter. In addition to that, I've also put some electrical tape on the back side of the cover there the ssd is just to create a "cushion" and/or barrier with it and the aluminum body. No issues since the install and very pleased. edit: You could essentially put any m.2 sata ssd, but it needs to be sata and not nvme (pcie).