I use a Chromebook and an Android phone (Samsung Galaxy S8+). Memory is not infinite unfortunately and I find myself saving a lot of 'important' and good to have files on my phone. thanks to micro-sd memory cards. The 512gb cards are out, but the prices are still up there. It also means that you can get a good deal (less a $100USD) on a 256gb card. Wandering Amazon, there are some no brand name cards that are extremely cheap and not what I would trust for my data storage. SanDisk has a 256gb micro-sd card that I would trust. I have used many SanDisk cards in my phones, camera and at one time as a data transfer device between my Windows laptop and a PC at a place I was helping out with a few things. I have not had a problem with SanDisk memory cards yet and plan on adding this card to my phone, to replace of the 124gb that I have in there now.
